XTS 5000 prgramming help (MDC/DCS)

[Scannergeek]

I was hoping someone could give me a tip on programming my new motorola XTS 5000 that I am hoping to use in receive only mode.

The transmissions in question are conventional APCO P25 w/ ? encoding vs. encryption. I was previously under the impression that this agency was encrypted, but have been told by a seemingly very knowledgeable source that these transmissions (base and mobile) can be received in the clear with an XTS radio if programmed correctly. I have the frequency, and NAC, but am only receiving some mobile transmissions, but seemingly not hearing the base.

I am new to commercial radio, but longtime scanner user and eager to learn. Can someone explain how these parameters should be programmed? (I know mechanically how to enter these, just not what the appropriate settings are):

For example, if the freq is 465.000, nac 365 (picked at random), how would I appropriately set the following parameters? I am intentionally omitting the actual frequency, NAC, and agency name out of discretion but can provide via pm if necessary.

transmit fx (input frequency?)
receive fx (output frequency?)
transmit NAC (?)
receive NAC (?)
transmit mode (digitial?)
receive mode (mixed?)
(PL/DPL are CSQ I assume)

Are there other coding parameters that I am missing that would be necessary for my radio to receive these transmissions? I have read references to "MDC" and "DCS" but am not familiar with these parameters. I have inferred that programming the correct DCS is critical. What are MDC and DCS? How do I program them in? How do I find the data for MDC/DCS as it pertains to these stations? Do I need RSS to program it or can it be done via the FPP? Thanks very much for any advice. I do understand the legal ramifications of posessing RSS or CPS software. Much appreciated by a newbie to commercial radio.

I'm pretty psyched this is a very cool radio.

Scannergeek

[Scannergeek]

Ok making some, albeit slow, progress on my own. I am thinking:

1) DCS is essentially "Motorola" for DPL, or NAC for digital comms, I believe. MDC relates to the system baud rate, I think.

2) I think programming the NAC (which I assume would be the same the Tx and Rx) would cover the DCS programming.

3) I would think that an XTS 5000 would be compatible with most MDC, or does this need to programmed into the radio?

4) still not sure how to determine what Tx freq vs. Rx freq (are these input/output?)

Starting to think FPP might not suffice, and that I will need RSS to make this work. I hope someone can clarify this for me.
I apologize for the really basic nature of these questions for most people on this forum. Thanks again for any advice.

[maxkelley_kc2spy]

OK, you don't need to work about DCS/DPL or MDC or any of these for a P25 digital system. All of those things have to do with analog systems.

All you would need to do is punch in the frequency you wish to monitor into the receive frequency, and set the receive NAC to $F7E, which is a special NAC which will open up the radio to any digital transmission it receives. And then set the receive mode to either mixed or digital (I prefer digital, if it's a digital-only channel..)

As far as transmit frequency, I'm not familiar with FPP on the XTS5K, so I don't know if there's a receive-only option, but I would set it to a junk frequency, like 462.5625, which is FRS channel 1.

As far as what frequency to listen to, if it's a repeated frequency, chances are, the repeater output is from 450-454.9975, or 460-464.9975. That's what you want to listen to, not the inputs of the repeater.

[Scannergeek]

Thanks Max!

If the frequency is 484.0875 repeated, how would I determine what the repeater output frequency is?

Also, does it sound possible to you that this will actually be monitorable to you? I've received some feedback on another site stating that I am not missing anything and the channel probably is encrypted.

I really appreciate any input. Thanks again!

Scannergeek

[maxkelley_kc2spy]

484.0875 is the repeater output frequency... I cannot say as to whether it would be encrypted or not, there's only one way to find out, is to try it!

[Scannergeek]

Ok here's what I don't understand. I am getting some transmissions on one frequency in the clear, some sounding garbled (encryption). At times the mobile units are clear, base garbled. Recently, it has switched and is now the opposite with the base in the clear. My question is, if one was using encryption, why would only half of the transmissions be encryptyed, the other in the clear? Or, is this, instead, a programming error on my part related to P25 encoding, and not actually encryption at all? Is it commonplace for encryption to be used on only selected transmissions (base or mobile)? Is it possible that I need a flashcode to decode the p25 being used (I am not referring to an encryption key. I do understand that if this is encryption that it is not monitorable). I just don't understand why some of these transmissions are in the clear if encryption is being used.