DSDPlus / FMP24 / SDR#

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therealjlh

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Dec 30, 2014
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Hey guys i am doing some research into the digital signals processing,

Is it possible to get any of these applications to give me a raw dump of the transmission stream?

I know that DSDPlus and SDR# have a raw output mode but i was wondering if it was possible to only record the data during an active transmission.

thanks
 

thewraith2008

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You will get everything in bandwidth you record. Target frequency and others the appear during time of record.

SDR# bandwidth is what ever the samplerate is set too when you record baseband and 32k for audio.
DSD+ is fixed to 96k samplerate for RAW dump.

By RAW do you mean IQ samples or demodulated data stream of the system eg. DMR, P25.
If the later then none of them output that stream. You would have to write your own program your use GNU Radio

Cheers
 

therealjlh

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Dec 30, 2014
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well i guess i didnt really pose my question using the proper terms.

I have a receiver of which i have an unfilter signal which i am piping into my line input on my audio card i was wondering if there is anyway to record that input only when the squelch level is broken and not all the time.

as part of a challenge from my signals class we were given a frequncy, signal bandwidth, and were told the trasmission would occure at seemly random intervals for the period of one week. our goal is to identify the signal, its coding method and determin the message given in the transmission. i guess what i was asking is does software already exist out there that can record the raw unprocessed IQ stream? as i have no interest in recording static or null data while i wait for the transmission to appear.
 

thewraith2008

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Nov 22, 2016
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If you are using a discriminator output of a scanner then I'm not sure if you can do it easily. Problem is the noise level (floor) is louder than the target signal level. Using Audacity's "Sound Activated Recording" with the "Sound Activation Level" won't work because of this.

SDR# "IQ from soundcard" won't work either because squelch is disable in this mode. Probably for the same reason.

A program you can use is called "Spectrum Lab" it has a triggered audio recorder. Lots of options, BUT.
It's is a complicated program to setup.

With a bit of trickery, you could use the audio out eg. headphones to trigger Spectrum Labs trigger on say the left channel and have the baseband on the right channel and set it to record stereo.

You can save as one file if say 10 transmissions occur over a week or save 10 files for the 10 transmissions over the week.

It works, I just tried it.

Cheers
 
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