Cutting out MDC-1200 chirps

Tim-B · Jul 20, 2017

I am monitoring some analog conventional 800 MHz frequencies that have MDC-1200 chirps at the end of the transmissions. Are there some settings that I can play with to cut out the chirps so that I don't hear them?

The transmissions do use a DCS of 025 and I have that set but I still hear the chirps. It would be better if they were at the beginning of the transmission then I could just set the P25 wait time to about 600 milliseconds and this would effectively cut out the chirp at the beginning. But unfortunately these are at the end of the transmission.

SCPD · Jul 20, 2017

To my knowledge you can only mute the data packet to make it a chirp. As for that if it's post id I do not recall a way to mute it any further in post id. You can try using hear clear check the box in the perosnality and it'll cut it some of the time or lower the mdc chirp. Keep in mind this is for motorola radios. As for a scanner I have never known one to mute mdc.

Tim-B · Jul 20, 2017

What does hear clear check the box in personality mean?

I am using a 396XT and a 436HP

SCPD · Jul 20, 2017

In radios capable it is a voice compression basically. There is many articles regarding use. Ideally all the radios should be programmed to use it for best performance. However I have seen mix and match in the field some using it some not. It's something you want all the radios to use if its used. It is basically companding the audio.

cmdrwill · Jul 20, 2017

DOS, data operated squelch is what Motorola calls the option to mute the MDC 'chirp'.

I do not know if the scanner has anything like that to mute the very annoying MDC swaking that drive some to drink or drugs...

doctordialtone · Jul 20, 2017

MDC1200

There's no way to mute it on a scanner since it comes across as analog audio.

INDY72 · Jul 20, 2017

CREEK CRICKCRICK... Sorry but you will always hear this sound on an scanner. CREEK CRICKCRICK chirp.

Tim-B · Jul 20, 2017

Yeah that's what I figured. I didn't see any way to do it either but I thought maybe someone knew of some clever setting like I mentioned with using the P25 wait time to cut it off if it was at the beginning. But unfortunately these are at the end.

RFI-EMI-GUY · Jul 21, 2017

Tim-B said:
Yeah that's what I figured. I didn't see any way to do it either but I thought maybe someone knew of some clever setting like I mentioned with using the P25 wait time to cut it off if it was at the beginning. But unfortunately these are at the end.

You might be able to build an outboard data operated squelch circuit (a simple tone decoder) and have that mute the audio fed into an audio delay circuit.

I am soon going to playing with audio delay chip , a circuit board from China that is a reverb, but I will be removing the echo feedback resistor. You can find these on ebay, it has a PT something chip. Very cheap. My application is for a VOX that doesn't truncate the audio.

Sent from my SM-T350 using Tapatalk

ProScan · Jul 21, 2017

Tim-B said:
I am monitoring some analog conventional 800 MHz frequencies that have MDC-1200 chirps at the end of the transmissions. Are there some settings that I can play with to cut out the chirps so that I don't hear them?

The transmissions do use a DCS of 025 and I have that set but I still hear the chirps. It would be better if they were at the beginning of the transmission then I could just set the P25 wait time to about 600 milliseconds and this would effectively cut out the chirp at the beginning. But unfortunately these are at the end of the transmission.

I don't have the problem. I just notch it out

55engine · Jul 23, 2017

I wish they would make MDC 1200 for the 4:36 536 scanner Like Whistler it only works on digital signal not analog I have a Motorola 2500 UHF that has MDC 1200 and it works wonderful I wish the scanner would work like that it would be nice to work for the LTR and conventional only works on the trunk systems

cmdrwill · Jul 23, 2017

ProScan said:
I don't have the problem. I just notch it out

Care to explain how you ' just notch it out' ?

55engine · Jul 23, 2017

Let's take my XTS 2500 UHF for an example every time somebody Keys up on the radio it comes to IDs that is MDC 1200 I wish the 5:36 and the 436 would do the same like I'll give you an example if it's dispatch talking it comes up one if it's Middletown Police and they're on their car radio it comes up C 182 that's just an example that means that's the car number if it's the portable and it came up with just numbers

Cutting out MDC-1200 chirps

Tim-B

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SCPD

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Tim-B

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SCPD

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cmdrwill

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doctordialtone

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INDY72

Monitoring since 1982, using radios since 1991.

Tim-B

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RFI-EMI-GUY

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ProScan

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55engine

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cmdrwill

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55engine

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