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I am searching for good recordings of distress calls emitted by American crocodiles, in particular by hatchlings. The longer the better. If not, also distress call recordings of other crocodilian species are fine.
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Differences in distress: Variance and production of American Crocodile ( Crocodylus acutus ) distress calls in Belize
Visit to that article
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The Fifth Generation (5G) mobile communication standard promises to provide enhanced mobile broadband, massive connectivity and ultra-low latency through various technological advances, including massive multiple-input multiple-output (MIMO), millimeter wave (mmWave) communications, and network densification. However, these technologies consume a lot of power and struggle to provide the users with guaranteed quality of service (QoS) in harsh propagation environments.
For example, the network’s total energy consumption scales linearly with the numbers of base stations (BS)s and the active antennas at each BS, while communication at mmWave bands suffers from high path/penetration losses. These limitations have resulted in the need for green and sustainable future cellular networks with control over the propagation environment.
Therefore, can Intelligent Reflecting Surface (IRS) be designed for 1 to 6 GHz bands as well? Or is it only suitable for high-frequency bands such as millimeter waves?
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Intelligent Reflecting Surface IRS be designed for 1 to 6 GHz bands:
1- Cascaded Channel Estimation for Intelligent Reflecting Surface Assisted Multiuser MISO Systems
2- Terahertz Multi-User Massive MIMO With Intelligent Reflecting Surface: Beam Training and Hybrid Beamforming
3- Wireless Environment as a Service Enabled by Reconfigurable Intelligent Surfaces: The RISE-6G Perspective
4- Joint Beam Training and Positioning for Intelligent Reflecting Surfaces Assisted Millimeter Wave Communications
5- Intelligent Reflecting Surface (IRS) Allocation Scheduling Method Using Combinatorial Optimization by Quantum Computing
5- A Path to Smart Radio Environments: An Industrial Viewpoint on Reconfigurable Intelligent Surfaces
6- System Performance Insights into Design of RIS-assisted Smart Radio Environments for 6G
7- Slotted Wideband Frequency Selective Reflectors for Sub-6 GHz 5G Devices
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Dears,
I'm a spatial planning master student, I'm studying the soundscape in Jordan- Amman, the methodology I will use is varied from a questionnaire (Soundwalk) to a binaural recording, and I'm wondering if you have any recommendation for questions to be asked in the Soundwalk?
Thank You
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Hello,
Will you conduct noise level measurements at the soundwalk stops? If so, you could ask about the perceived loudness using a scoring method and then correlate the objective and the subjective results.
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Intelligent reflecting surface (IRS) is deemed as the promising and revolutionizing technology for future wireless communication systems.
As the kind of impedance metasurface, each element of IRS is composed of configurable electromagnetic (EM) internals and can reflect the incident EM wave with the desired phase shift. Thus, the IRS is able to intelligently change the propagation environment and significantly enhance the quality and coverage of wireless communications. So, do you see any chance that network operators will deploy the IRS in their networks?
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Yes, IRS can be deployed to enhance security in communication networks to either replace legacy security solutions or supplement them.
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If the range of transmission power without IRS is too high, and the BS has at most 40 dBm. How can we have high range transmission of power?
where IRS is the intelligent reflective surfaces, and BS is the base station
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IRS or no IRS, isn't this a standard problem of propagation loss? You have to know the sensitivity of the receiver, the noise power at the receiver, the gain of the receive antenna, the range to the transmitter, the terrain characteristics, and consequent signal loss along the path, and the transmit power and transmit antenna gain.
Now, without IRS involved, you can compute the signal to noise ratio at the receiver, and determine if communications are possible, using a given type of modulation. There will be different marginal SNR requirements, depending on type of modulation you want to use. Shannon's equation can be used, to predict the maximum possible channel capacity, along a single propagation path, with a given channel bandwidth and SNR.
I'd say that using IRS, at either or both ends, is much the same as changing transmit and/or receive antenna gain.
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IRS can create higher beamforming gain with the help of an “intelligent” reflector. But, this brings other practical issues.
How does BS/AP synchronize with the reflector about the amplitude and phase?
where IRS is the intelligent reflective surfaces, BS is the base station and AP is the access point.
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The basic algorithms for phase configuration and channel estimation are described in our tutorial article: https://arxiv.org/pdf/2102.00742.pdf
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which means another IRS receives the signal from the first one and sends the signal toward another one and so on.
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Welcome!
As far as I understand the IRS is one hop network component. If the path from the source to destination has low transmission coefficient such as deep fading of massive blocking then one can use one ore two IRSs to convey the signal to the intended receiver or destinations.
Incase of more that one IRS all of them receive their incident waves from the intial source such as the base station. I think multi hops may cause excessive delay.
Best wishes.
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where IRS is intelligent reflective surfaces.
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An IRS is a new type of relay, with specific characteristics, benefits, and drawbacks. This is discussed in our recent magazine article: https://arxiv.org/pdf/2006.03377.pdf
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where IRS is intelligent reflective surfaces, ISI is inter symbol interference which is a main cause that can reduce efficiency of the system due to multi
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The increase in a delay spread caused by an IRS is rather small, so ISI isn't really the problem. However, when an IRS is tuning the propagation environment for one communication link, it can accidentally cause interference to other communication links (in the same or different bands).
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Is it possible to mention the areas in which IRS have been used? And how much benefit have you achieved or will be achieved when using it?
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welcome!
I think the IRS technology for controlling the the wireless transmission parameters will undergo tremendous research to apply them in the the 6G mobile communication networks.
I think I wrote about this before for answering one your questions on this topic.
To be aware of the challenges and difficulties with the introduction of such devices please follow the paper in the link: https://hal.archives-ouvertes.fr/hal-03020450/document
Best wishes
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Intelligent reflective surfaces (IRS)
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Dear Abbas,
See below some stuff that can be of interest regarding your question:
Which is the best reading in reconfigurable intelligent surfaces?
IEEE Communications Society Emerging Technology Initiative (ETI), “ Reconfigurable Intelligent Surfaces ”.
Best Readings in Reconfigurable Intelligent Surfaces ...
What is the physical principle of an IRS?
The physical principle of an IRS is that the surface is composed of atoms, each of which acts as an “intelligent” scatterer: a small antenna that receives and re-radiates without amplification, but with a controllable phase-shift. Typically, an atom is implemented as a small patch antenna terminated with an adjustable impedance.
Intelligent Reflecting Surfaces: On Use Cases and Path ...
When is a transformation called an isometric transformation?
If there is no change in size or shape, then the transformation is called an isometric transformation. If the size of the object changes then the transformation is called a size transformation. Each transformation has a unique set of characteristics or rules that define the movement.
16.Transformation Geometry (SC)
When does a reflecting surface have a beam width?
“Mirrors” exist only in textbooks, when a plane wave is impinging onto an infinitely large conducting plate (none of which exist in practice). Irrespective of how the IRS is constructed, if it is viewed from far enough away, its radiated field will have a beam width that is inversely proportional to its size measured in wavelengths.
Intelligent Reflecting Surfaces: On Use Cases and Path ...
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The researcher, scientist, or engineer who uses mathematical optimization, or more generally, computational mathematics. This includes, naturally, those working directly in optimization and operations research, and also many others who use optimization, in fields like computer science, economics, finance, statistics, data mining, and many fields of science and engineering. The primary focus is on the latter group, the potential users of convex optimization, and not the (less numerous) experts in the field of convex optimization.
An intelligent reflecting surface (IRS) comprises an array of IRS units, each of which can independently incur some change to the incident signal. The change, in general, may be about the phase, amplitude, frequency, or even polarization.
To date, in most studies, the change is considered as a phase shift only to the incident signal, so that an IRS consumes no transmit power. In essence, an IRS intelligently configures the wireless environment to help the transmissions between the sender and receiver, when direct communications have bad qualities. Example places to put IRSs are walls, building facades, and ceilings,
Therefore, the optimization algorithm solves the achievable problems by optimizing the phase shifts by considering both continuous phase shifts (CPSs) and discrete phase shifts (DPSs).
How can benefit from Convex Optimization when using intelligent reflective surfaces in wireless communications?
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Dear Abbas,
I will recommend the article https://arxiv.org/pdf/2104.01421.pdf
I hope it will be worth reading about your problem.
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In essence, Intelligent Reflecting Surfaces (IRS) intelligently configures the wireless environment to help the transmissions between the sender and receiver, when direct communications have bad qualities. Example places to put IRSs are walls, building facades, and ceilings. But, is it possible to benefit from the use of the Intelligent Reflecting Surfaces (IRS) for satellite communications?
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Yes, you can use the technology at any frequency band and for many different use cases. The main question is what kind of problem the addition of an IRS will solve. One possibility is to deal with Doppler effects: https://arxiv.org/pdf/2006.06991.pdf
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The intelligent reflecting surface (IRS) aided wireless communication system, where the IRS has emerged as the revolutionizing solution to enhance wireless communications by intelligently changing the propagation environment.
One of the aims of the wireless communication system with IRS is to minimize the transmit power while guaranteeing the qualities of both primary and secondary transmissions. As in communication between a multiple antenna Base Station (BS) and a single antenna user, assisted by an Intelligent Reflecting Surface (IRS); and Due to the large number of elements in IRS, acquiring Channel State Information (CSI) requires many radio-frequency chains and considerable training overhead.
Therefore, what is a new method based on the Optimization to optimize the problem of beamforming at the BS and IRS without CSI, by minimizing the transmit power, subject to a minimum signal-to-noise ratio (SNR)?
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There is a set of problems found in smart reflective surfaces, including:
1. the secrecy rate maximization (SRM) problem is formulated, which is a non-convex problem with multiple coupled variables.
2. The nonconvexity problem of maximizing the weighted sum rate (WSR) of all users when the BSs and the users are equipped with multiple antennas, which enhances the spectral efficiency by exploiting the spatial multiplexing gain.
3. The optimization problem of maximizing the weighted sum rate (WSR) of information receivers (IRs), the transmit precoding (TPC) matrices of the base station (BS) and the passive phase shift matrix of the IRS jointly.
4. The signal-to-noise ratio (SNR) grows linearly with the number of array elements N when using Massive MIMO receivers and half-duplex relays.
5. properly altering the signal propagation via tuning a large number of passive reflecting units.
6. the secrecy rate of the intelligent reflecting surface (IRS) assisted Guassian multiple-input multiple-output (MIMO) wiretap channel
7. maximize the spectral efficiency of an IRS-assisted point-to-point multi-input multi-output (MIMO) system
8. enhancing its secrecy rate for an intelligent reflecting surface (IRS) assisted Guassian multiple-input multiple-output (MIMO) wiretap channel (WTC).
What parameters can be used when improving the performance of intelligent reflecting surface (IRS) by optimization algorithms?
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welcome!
It is so that the the signal path from the base station shows multipath effects such as fading to the user site.
The addition of the IRS will introduce an alternative path where the signal will be recieved by the IRS phase shifted and amplitude changed and directed to the the site of the user equipment. So the signal path through the IRS must has better transmission properties which means higher signal to noise plus interference at the user site.
So, Accordingly one has to maximize the signal to noise plus interference ratio.
Best wishes
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One of the most important modern systems used in wireless communications is the intelligence reflective surfaces. Are there filters used with these surfaces?
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Adding to the respected colleagues, the IRS are made of a two dimensional array of sub wavelength patches provided by pin or varactor diodes such that one can phase shift and control the amplitude of the reflected wave from each patch.
One can control the phase shift by changing the diode bias. The diode is sufficient to change the phase shift from 0 to pi.
Where you want to insert the filter and why?
For more information please refer to the presentation in the link:https://www.ltu.se/cms_fs/1.203003!/file/Emad%20Ibrahim.pdf
Best wishes
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Can new optimization algorithms be designed to work infinitely to get the best results, they search the entire search area in a spherical manner and are concerned with all static and dynamic particles and possess all physical and topological properties to achieve the best possible solution?
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I am looking for research/papers (if they exist) that describe acoustic signalling in elasmobranchs. My google searches are giving me no love so far, but it could be a matter of terminology. Essentially, I am looking for any research that describes any elasmobranch species producing sound / acoustic signals.
TIA for any leads!
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Hi Joni,
I have always referred students who ask about basic acoustic processing in sharks, skates and rays to this now classic paper by Jeff Corwin:
Corwin J.T. (1981) Audition in Elasmobranchs. In: Tavolga W.N., Popper A.N., Fay R.R. (eds) Hearing and Sound Communication in Fishes. Proceedings in Life Sciences. Springer, New York, NY. https://doi.org/10.1007/978-1-4615-7186-5_5
Of course if you are specifically interested in the acoustic "signals" produced by these animals rather than the detection of such signals, then I will keep looking.
Hope this helps.
Peter
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It is accepted that bats communicate with bats of the same species, and the frequency of this is indicative of the bat species. But can bats communicate with those from another species?
We are licensed to care for bats in the UK, and those who are in our care and that we are rehabilitating are common pipistrelles, apart from one other, which is a Natterer's bat. He is in a tank by himself but in the same room as the pipistrelles.
He will be aware of the presence of the pipistrelles, who clearly communicate between themselves, but it would be good to know if he could communicate with them to some degree. He will be with us for a bit longer; he still has a wing that is weaker than the other, and could not fly well enough when we tested him to allow him to survive in the wild. And winter (and hibernation) will be coming.
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follow
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How many interfacial SH-waves can propagate in the PEMs?
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My pleasure Dear Prof Aleksey. Regards
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I am currently working on anthropogenic effects on the vocalisation of howler monkeys in the urban environment.
I record the vocalisations with a TASCAM DR-07MKii and I want to extract acoustic measurement such as frequency, pitch, rates and lengths of vocalisations.
Which program is easiest to use for a beginner to extract these variables?
I currently have: Sound Analysis Pro, Praat and Audacity.
All tips and additional information are very welcome
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I agree that Audacity is of no use-- it's primarily an editing program, not for measurement. Praat and SAP would both probably work for the simple measurements you described. I believe Praat (which was developed for work on speech) has some tools for measuring speech-related features such as formants, which might be useful for nonhuman primate vocalizations. Raven Pro (http://ravensoundsoftware.com/) has (I'm told) an easier learning curve than Praat and includes basic time, frequency, and relative power measurements (though no formant measurements). There's also a set of freely available tutorial videos available (see "Training" on that website).
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In underwater acoustic communications, medium of propagation is water in which propagation of speed of acoustic signal is different from air. Need to identify which simulators are providing this flexibility of changing propagation medium?
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  1. NS-3
  2. AquaSim (NS-2 based)
  3. QualNet
  4. SUNSET framework
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Electronic Fetal Heart Monitoring can be done by listening to your baby's heartbeat with a special stethoscope. More often, it is done using two flat devices (sensors). They are held in place with elastic belts on your belly. One sensor uses reflected sound waves (ultrasound) to keep track of your baby's heart rate. The other sensor measures how long your contractions last. The sensors are connected to a machine that records the details . can the phone be used for recording this signal?
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Hi everyone,
I am writing my MSc thesis about vocal communication in woolly monkeys and I want to make a general description of their different types of calls. I want to obtain various acoustic parameters such as duration, frequency range, low frequency, high frequency, maximum amplitude, average frequency, initial frequency, and final frequency. Hence, I have to analyse my recordings using SoundRuler, but I've never used this software before. I've read the instructions but I have some questions anyway.
- I recorded in stereo, so when I introduce the recording in the software, it asks me if I want to analyse left or right channel. Can I analyse both separately and then calculate the mean of both channels?
- Also, when I introduce the recording, I mark the section that I want to analyse using green bars. Once this section is marked, I proceed to do the analysis. Is it as easy as clicking the "manual" button? When I do it, it appears a table with the different values of the parameters, but I don't know if it is as "simple" as that.
That's all at the moment. Thank you for your answers!
Laura.
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Hi Laura,
I agree with Pavel regarding the channels and amplitude. I also don't use SoundRuler (sorry!) but I thought it might be useful to add that you need to be sure there is no background noise overlapping your calls of interest. If for example these recordings were made at a zoo, there may be visitors chatting, or in the field there could be other animals calling etc. on your recordings. If there is, then you can either need to filter it (if it does not overlap in frequency with the monkey calls), or if that's not possible, you could manually extract the frequency measures, or simply eliminate those calls from your analyses. It might be that you can use the read-out on all your "clean" calls (i.e. no background noise, one individual calling at a time) and in that case it could be just as simple as you say!
Good luck with your interesting project!
All the best,
Esther
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i am trying to evaluate the benefits of UAC
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I was monitoring a lobster and noticed it was clearly resonating through its carapace (just ahead of its tail section in the spot they're easily held). Everything on the web seems to focus on them using their antennae and file, is this a common communication mechanism as well? attached is a snippet where he seemed to "tell me off" before walking back into his mangrove.
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It seems reasonable that fish can measure intensity if they have a lateral line and a swim bladder. I am asking if anyone has tested their ability to measure complex intensity rather than time as averaged, e.g. only real intensity?
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Dear fellows,
I've been watching your discussion related to "Do fish measure reactive intensity?" and found it interesting when talking about "total sound intensity from a pure acoustic point of view". When it comes to sound reception/sensing in fish you've forgot the "most" important sensor beside the swim bladder and the lateral line, i.e. the otoliths, which act like an accelerometer. There is some literature related to this which may clarify/elucidate sound reception in fish in relation to total sound intensity. I'll like to see you++ continue with this discussion.
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I am looking for a way to estimate particle acceleration of an underwater sound produced by aquatic animals, per e.g. Something easy to use in the field and reliable. Like a vector sensor or an underwater geophone?
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Some of the Wilcoxon sensors were developed with the US Gov't, and have ITAR restrictions associated with them.  They are not available internationally.  Applied Physical Sciences also has some sensors, but they too have ITAR restrictions.  The Microflown/Hydroflown sensors (from the Netherlands) have never been proven to be effective in underwater applications. 
My recommendation would be to get several good pressure sensors and build your own vector sensor based on pressure gradient measurements.  (I believe that's really what the PAS is.)
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What is the relationship between transmission power and transmission range when communication medium is acoustic or radio? I'll appreciate if you can suggest a mathematical equation for this.
suppose I want to increase the transmission range from 600 meters to 700 meters. For this I'll need to increase transmission power. If x is the transmission power that results in transmission range of 600 meters then what should be the value of y where y is the transmission power that results in transmission range equal to 700 meters. In short what should be the equation to calculate transmission power base on transmission range?
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Imagine your transmitter is isotropic (transmits equal power in all directions) and the medium is lossless. You can now think of the signal as an ever expanding spherical wave front. Because the total power is constant, and the area of the sphere increases with the square of the radius, the signal power at each point of the sphere will be inversely proportional to the square of the radius (their product should be constant). For this reason the signal power at 700m will be (6/7)^2 of the signal power at 600m. The power should therefore be increased by a factor of (7/6)^2 to compensate. This rule is based on the conservation of energy principle and holds for every possible type of radiation (radio, acoustic, light,...)
In reality the transmitter is typically not iostropic but that does not matter, the principle stays the same.
For the case of electromagnetic radiation there is a nice mathematical formula called the "Friis transmission equation". Google for more info.
Good luck with your research!
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Dear all, how do i normalize my data if not normalized by applying log 10 and sqrt transformation?. 
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depends on data which transformation to apply. available in standard texts
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Hello all,
I'm interested in attaching a small audio recorder to large mammal radiocollars and having them record continuously for 1 month.
Minimum specifications:
1. Would need to store 750 hours on audio and run on a single charge. Ideally, it would have a sampling frequency of 22kHz (but this isn't essential and battery life trumps sampling frequency).
2. Combined recorder and battery weight < 150 grams
3. Recorder and battery price < $250
Does anyone know of any recorders that fit the bill straight out of the box, or that could be modified by someone with little electronics experience?
A previous study on chipmunks used a spy microphone (http://ts-market.com/products/models/1258/) for their project. That would also work here if there was a way to change the power input to something that would last 1 month (storage on the device is enough for 1200 hours).
Having said that, the unit cost of the above device would probably exceed my budget so if anyone is aware of something cheaper that would be great.
Thanks in advance for your help.
Kas
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as mentioned before there are two problems, storage and batteries. Among small digital recorders the best one is the SONY PCM-M10, unfortunately now discontinued but still available in US. Its power consumption is among the lowest: 60-70mAh, that means >30 days continuous recording with 6 or 8 D size batteries (max 18Ah at 1.5V), that brings weight and size high. As an option you could use Lithium D size batteries, expensive but with double power than alkaline (up to 19Ah at 3.6V).
As for the storage the M10 is one of the very few that is declared max 32GB but can record on a Sandisk Ultra 128GB microSDXC formatted by a PC in FAT32 mode. The max microSD size now available is 200GB but I never tested it in the SONY. Huge size available; however, to record 30 days you necessarily need to switch to MP3-320K with a bandwidth of 15 kHz, that is more than with 22k PCM sampling.
In 22kHz PCM stereo (few recorders can record in mono !) you need 228GB/month that would be possible with a standard 256GB SDXC card (these are also available up to 512GB now). But recorders are larger and more power hungry.
Solutions based on microcomputers need too much power. In any case the first feature you must check is power consumption. A recorder that would partially fit your needs is the Tascam DR22WL, it records in mono and thus 1 month could fit in a 128GB microSDXC card. Unfortunately it requires near to two times the power required by the SONY M10. If you solve the battery problem the WL 22 is the good solution.
Another option to be deeply tested before going on is to use the ZOOM H1. Smaller and lighter than the SONY, It is declared to max 32GB microSD however it can record on larger memories as the SONY (to be tested on specific memory brands and to be tested for power requirements).
Eventually write me privately for alternative options.
Gianni
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I’m making research about the possibility of fetus hearing perception (in terms of Hz).
We know that the future baby has a important preference to the mother’s voice. This voice arrive to the fetus by the spinal column and the sound is very high in tone.
Due to the fact that high tones are stimulating for human metabolism, fetus hears ultrasound and, from the other side, people older than 30-40 years are not yet able to hear more than 15-17 KHz, the question is:
Is it possible that the fetus has a specific Hz range hearing, able to listen to very high frequency like ultrasound and this capacity slowly disappears in perinatal life?
I’d like to listen to your opinion, that I consider very important for me.
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According to 'Development of fetal hearing' by Peter G Hepper and B Sara Shahidullah, the high frequency range you are interested in was not considered in this study however it says that early in gestation 'none responded to the 1000 Hz and 3000 Hz tones'...so one can extrapolate...but it is all about hearing perception.
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I am working on acoustic communication in Orthoptera species. Turbolab is very effective for get good quality printout after analysis. But I would like to use more user friendly software. 
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Hi Mushtaq 
thank you. I am sorry for late response.
I will try Pulse lab.
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It is an aspect I am looking at for my Honors project, but it seems nobody ever looked at the influence of loud music on social behavior. Plenty has been researched on how different aspects of music (tempo, loudness, genre etc) effects shoppers, increase/decrease sales, makes you drink more, but I cannot find anything related to influencing the social behavior in public spaces (bars and pubs).
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There is one paper. It's related to nightclubs though, rather than specifically pubs and bars. http://herd.typepad.com/files/hendrie_etal_2009.pdf There's not much there in relation to music, but it does make the point that because nightclubs are generally quite loud and dark, that it promotes lekking behaviour. (Pg. 1344). There's also a section on dancing displays (Pg 1336).
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I am searching for good song recordings of African Reed Warblers. The longer the better. Or maybe somebody works near the habitat of these birds and it's not a big deal to record several minutes for me :)
There are some recordings on xeno-canto.org, but they are way too short for the analysis :(
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In Yellowhammer Dialects project, I am exploiting many sources of recordings:) Surprisingly, some yellowhammer song are also on Flicker, however I bet this is not the case of African warblers.
The best would be to contact British library - they have about 47 songs: http://cadensa.bl.uk/uhtbin/cgisirsi/?ps=jvO7LMNQhB/WORKS-FILE/325200049/123 I will send you a contact to a responsible person through email, Nika:-)
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Basically, I want to know how we define the near field and far field in terms of distance between antenna/microphone array and source.
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Mohan, this answer is for the antennas in electromagnetics. The electromagnetic field associated with an antenna is the Fourier Transform of the current aperature distribution of the antenna. This depends greatly on the shape and feed design of the antenna. An added complication is that the time variations of the current introduce solutions to the math that involve a far field and a very complicated near field.
Think of it this way.  The electromagnetic radiation that propagates away from the antenna, never to return, is governed by the far field and obeys the inverse square law for propagation distance. The near field is much more complicated and involves higher order inverses and the fact that the energy in the near field does not propagate. It expands and contracts in response to the frequencies of the excitation current. However the energy is exchanged by the electric and magnetic field as is the normal case of propagation.
I forget the formulas for how far the near field extends from the antenna but I know that the higher the effective gain, the further the near field extends. In some very large gain antennas, the near field may extend 800 meters! Good luck.
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Is there any proper literature on methods of syntax analysis in bird song except first order Markov chain?
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Dear Veronika,
You might want to look at Birsong, Speech and Language (Bolhuis and Everaert, 2013).  There's a number of nice pieces in that book and I'd recommend reading ten Cate et al.s' chapter 12:  "Analyzing the Structure of Bird Vocalizations and Language:  Finding Common Ground", where they discuss a variety of techniques.  
Best regards - Marie
Bolhuis, J. J., and Everaert, M. (2013). Birdsong, speech, and language : exploring the evolution of mind and brain (MIT Press, Cambridge, Mass.).
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I'm working with sound emission of Netrosoma (Orthoptera) from Mexico, together with Paolo Fontana. We are trying to understand which body parts are involved in sound emission since some spp are without stridulatory file.
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I agree with Charles Henry about anatomical validation. In our lab we have modified a GoPro action camera (which records at 240 frames per second and fantastic resolution) with macro lenses and have been getting incredible "high speed" video of echolocating bats for a fraction of typical high speed camera costs. Contact me directly if you'd like more information on this setup--all the components are available commercially from various companies.
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Can we use EM waves >100kHz for underwater communications? Is there any possibility of OFDM-based system for underwater communication?
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Dear Mir
A communication link consists of a transmitter , a receiver and a communication medium. Every medium has the suitable signal energy form to propagate easily in it.
Good electricity conductors such as metals are conveyor of electricity.Therefore transmission lines are made from metallic conductors like copper and aluminium.It is not practical to connect the transmitters and receivers in underwater by transmission line.
Therefore one uses the suitable wireless system for under ware communication.
Basically there are two basic wave types, the acoustic waves and the electromagnetic waves. Sea water is salty and therefore good conducting as Dr Garry mentioned. Consequently it attenuates the electromagnetic waves and this attenuation increase as the frequency increases. Only low frequency electromagnetic waves are capable to propagate an appreciable distance before it gets undetectable.Therefore the radio wave under sea water communication is restricted to very low frequency waves with very small band width and consequently very low data rates. Newly, short distance under water optical communication links are developed operating in the wavelength range from 0.4 to 0.55 micrometers.They can be considered also wireless electromagnetic wave communication.
As a medium the sea water as a fluid is suitable for acoustic wave propagation. Therefore, the under water communication systems are normally
based on acoustic wave transmission. Here piezo electric transducers are used to convert the electrical signal into acoustic waves and vice verse. The rest of the system remains the same.
As a communication medium its carrier frequencies are limited and consequently the
channel bandwidth. The power is limited because it is mostly battery operated system. The propagation speed is relatively small and hence larger delay time and delay time spread. Therefore, the link data rate is relatively small and limited.
From the principle point of view, OFDM can be used as a modulation technique to overcome multipass fading. occurring also in acoustic wave communication.
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I would like to convert sound energy of 120 db into electrical energy. This 120 db is obtained from the ship engine. Though it requires many cascading stages of pre - amplifier. How much would be the viable amount of power obtained?
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120 dB is one watt per square meter. I leave you to figure it from there.