G,

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From: "Stefan Schäfer" <[email protected]>
Sent: Saturday, March 08, 2014 8:11 PM
To: <[email protected]>
Subject: Re: LF: Microphone via WLAN (WiFi) ?

Hello Mauro, Clemens, Graham,

Your examples are in principle what i need but in these systems, the dynamic range is much to low, maybe 40...50 dB. Some years ago i played arround with some Bluetooth headset, which has a microphone input of course. But the results were very poor.

Also, the backgound noise reduction is an unwanted feature here, as well as an AGC.

I think, i the todays world, it should be "easy" to combine a SMD ADC (those from the cheap soundcards) with a SMD WLAN IC (those from the cheap USB WLAN adapters, giving some 10 mW to some 100 mW output power). But i don't know anything about the communication between these 2 ICs, protocols, configuration, etc. etc.

Am 08.03.2014 16:21, schrieb Graham:

[...]
MIC <>  USB SOUND  CARD <> USB/WIFI ~~~~~~~ WIFI/USB<>PC

But you did forget something! Actually you must write:

MIC <>  USB SOUND  CARD <> PC/Netbook <> USB/WIFI ~~~~~~~ WIFI/USB<>PC

And this is what i don't need. The power consumption, weight, size, costs are to high and a PC is not necessary.

But now i found this: http://www.amazon.de/Kamera-%C3%9Cberwachungskamera-Empf%C3%A4nger-Zubeh%C3%B6r-Wireless/dp/B004AZL6AE/ref=pd_cp_ce_2

It is a WLAN camera+ audio. Actually i don't need the camera, just the tone. The remote system runs on batteries, just as i need. Maybe the camera can be removed or disconnected. The question is, what is the dynamic range and frequency range (0...24 kHz?, maybe not!) and are there any "sound effecs" which are unwanted here. 49 EUR, that would be fine if it works as desired. Maybe the audio chip could be replaced by a better one?! But maybe it is all in one...

Has someone ever played with such a system or are there alternatives that i didn't found so far?

Sounds like OT but such a system could be a revolution for LF/MF/VLF reception, when thinking about local QRM problems!

73, Stefan/DK7FC






Am 08.03.2014 16:29, schrieb IK1WVQ Mauro:

Hi Stefan

it is not completely compliant to your requests, but, if you do not find the right equipment, you can consider the "baby monitor" at 860 MHz .. some units are digital, and you can route the sound output to the line input of the sound card of your PC .

In free space, without antennas, you can obtain near 300 meters..

the system is "near" legal (you can consider your new VLF receiver as a "baby" !!! hi!)

73 de Mauro IK1WVQ

At 15.08 08/03/2014, Stefan Schäfer wrote:

Hi all,

Again i spent some time to find a module which allows to transfer a mircophone input signal via WLAN to the PC. Without success...

To make things clear:

The system has to consist of to parts:

1: The first one is battery supplied and has a microphone input (like a cheap external USB soundcard) and a WLAN output, using an external antenna and SMA plug. I.e.: Input: 3.5mm microphone jack. Output: SMA WLAN antenna connector. 2: The second part is connected to the PC and is a WLAN receiver that appears as a normal external USB soundcard and allows to receive the audio signal from the first part of the system.

The system allows to run a /p receiver for VLF or any other band.

An expert could create such a circuit for himselfe but i need to buy something like that, if it is available. But all i can find in the web is the opposite way, i.e. people who want to transfer their sound from the PC to a /p loudspeaker or headphone, argh... Or, a big device which includes a real big microphone (dynamic range ???). These are expensive systems.

However, external soundcards are cheap and WLAN modules are cheap too.

So, isn't there such a device for a few EUR in the web, these days? It has to have a dynamic range of at least 100 dB, like the 2 EUR external soundcards at amazon do (with some luck).

Any help is much apprechiated :-)

73, Stefan/DK7FC