Beginner DSD and scanner question

[hsieh]

This is my first post here.I live in Taiwan.I know that there are P25 and some sort of digital EDACS system nearby and want to decode them with DSD. What kind of scanner do I need?Do I need a trunk tracking scanner capable of tracking EDACS or any conventional analog scanner with discriminator tap will work?

Thanks

 

[n4yek]

Any scanner with a discriminator tap will do. DSD is only decoding audio, it doesn't matter what your scanner is doing or capable of doing just as long as an audio feed is being fed into your computer.

 

[hsieh]

But in a trunking system,frequency will change every time a user transmits.So will I need a trunk tracking scanner that can follow the always changing frequency?

In my area,P25 uses VHF band and digital EDACS uses 400MHz band.

 

[n4yek]

If you are needing to follow a P25 or EDACS digital system, you will need a digital scanner to do it with and then DSD becomes un-needed.
A normal trunk tracking scanner will not track a digital system.

If you use a conventional scanner with a tap, just enter the frequencies of the system you are wanting to monitor and scan that way. You will not be able to follow any particular agency using DSD if the freqs are part of a trunk system, but at least you will be able to hear something.

 

[ay00]

I was under the impression that a second computer-controlled radio was needed with Unitrunker to tune into a trunked system. The radio with the discriminator tap monitors/gets info from the control channel and the second (computer-controlled) is used to tune into an active frequency when it comes up. I'm still a newbie so I might be wrong

 

[vans113]

you can use uni trunker with it also. I have no experience in this at all. I have a bct 8 with a tap i listen to provoice on. Just for regular edacs also you don't need dsd you can listen to them out in the open unless they are digital.

 

[Tweekerbob]

I was under the impression that a second computer-controlled radio was needed with Unitrunker to tune into a trunked system. The radio with the discriminator tap monitors/gets info from the control channel and the second (computer-controlled) is used to tune into an active frequency when it comes up. I'm still a newbie so I might be wrong

That is correct. But if you are trying to decode any digital comms on the trunked system, the second receiver will have to either be a digital capable receiver (probably defeats the purpose of the first radio and Unitrunker as noted in another post) or it too would need a discriminator tap piped into a second soundcard piped into a running copy of DSD.

So to follow a P25 trunked system without having any digital receivers, you will need one analog receiver (with tap) tuned to the control frequency. That discriminator audio is going to Unitrunker. Unitrunker will control a second receiver (again with tap) and tune to the voice channels as they come up. The second receiver's discriminator is fed into DSD and out pops the decoded audio. Pain in the a$$, but's that's P25 trunking on a budget.

 

[Spitfire8520]

You may want to consider the SDR (especially SDR# and RTL2832U USB TV receiver) rather than investing into a scanner. You can look it up on the internet using the keyword "RTLSDR". The reason I recommend this is that the Taiwan, as a whole, doesn't appear to have many radio frequencies documented, so a scanner may not be able to provide what you want. There's potential of TETRA systems and encryption that may make it impossible to hear any traffic regardless of the scanner. I would also be hesitant at a trunked tracking scanner as EDACS requires you to know which frequency is which LCN and digital scanners may or may not work depending on if it is conventional or a trunked system and other technical details involved in this. You don't have to follow this advise and can still get a scanner if you want.

A RTL2832U is cheap compared to a scanner and gives you a really wide range of frequencies to monitor, and can be run through SDR and Trunked Radio Decoders (link) such as UniTrunker. Another good thing is that you do not need to perform a semi complex discriminator tap on a scanner to be able to use DSD and UniTrunker. If you buy two of them, you can have one monitoring a control channel and have UniTrunker use SDR# and the other one to try to follow conversations such as some of the videos seen below. I don't actually know much details about this, but I'm sure the SDR community has some information regarding this and can be researched before making your decision. If you chose RTL, you might also want to look at some antenna options to increase your radio performance.

Trunk tracking and voice following with UniTrunker and SDR# using the FCD and RTL2832U+E4000 SDR - YouTube - UniTrunker and SDR
PC P25 CT State Police Trunk Tracking Scanner (DSD, Unitrun - YouTube - P25 and UniTrunker
RTL-SDR: Decoding P25 Phase I QPSK with DSD and SDR# - YouTube - P25
UNITRUNKER+DSD+X2-RTL2832u-tracking Edmonton's analog/digital.edacs system using two dongle - YouTube - EDACS and UniTrunker

 

[hsieh]

I tried the RTLSDR before and tried to listen to the 2 meter ham band and aircraft band.It didn't work very well.The sound quality and sensitivity is poor.I use a 1 meter long metal rod as my antenna.Then I bought several used scanners.With a 50cm telescoping antenna,I can get much better sensitivity and sound quality.

I am considering a new scanner because my scanners are old or stop working and I want to receive digital signals.

In Taiwan,there are a still a lot of analog signals to receive.But many users start to switch to digital such as P25 .MOTOTRBO or TETRA.