Is the simulcast issue exclusive to P25 sites or can it also happen on Moto Type II sites as well?
Encrypted frequencies
- Thread starter vashooter
- Start date
- Status
kc4jgc
Member
Exclusively a digital issue.
slicerwizard
Member
Some Type II systems are simulcast and can carry digital voice, so why couldn't there be simulcast issues with them?
Multipath / "simulcast distortion" can happen on both P25 digital simulcast sites and Moto SmartZone / Smartnet (and EDACS) analog or hybrid simulcast systems. Monitoring P25 simulcast systems using a receiver not specifically designed to receive them is likely to be unsatisfactory. Analog simulcast systems can also present simulcast artifacts / effects, but generally the transmissions are readable and not usually blanked - unlike P25 digital voice. Legacy Moto SmartZone systems that use P25 CAI (voice) can also suffer from simulcast effects similar to more modern P25 simulcast systems.
If you want to save some money, there are other solutions you can use to monitor P25 systems using free or inexpensive software, and $30 SDR receivers. They work best when listening from a fixed position, but can be used in the field as well.
Last edited:
Think of it as a "cell" containing 2 or more physical locations all identical with the same frequencies, talk groups and control channels. To the system it looks like a single site with a large coverage area. A simulcast cell can be part of a large multicast system.
The Charlottesville-Albemarle system is Type II with digital voice. There can be simulcast issues with it, but those issues seemed to affect older Uniden scanners more than GRE/Radio Shack/Whistler scanners. However, GRE/Radio Shack/Whistler scanners generally do not do well with P25 simulcast. There are exceptions, usually caused by being in a "sweet spot" - a location where the simulcast effect is somewhat negated.
As another person indicated, when you are listening to analog on simulcast, the problem is not really noticeable. It's the process of decoding digital signals that gets messed up on scanners not built to handle simulcast.
And you can have SIMULCAST DMR and P25 Conventional Simulcast.
kc4jgc
Member
I haven't had simulcast issues with Charlottesville/Albemarle County at all.
When Chesapeake had Motorola system, their PD & FD were digital but had no simulcast issues at all. I could even receive the system reliably miles beyond city lines. When the city upgraded to P25, simulcast distortion became a huge issue and I can no longer receive much beyond city lines.
When Chesapeake had Motorola system, their PD & FD were digital but had no simulcast issues at all. I could even receive the system reliably miles beyond city lines. When the city upgraded to P25, simulcast distortion became a huge issue and I can no longer receive much beyond city lines.
Newer systems also use directional antennas to reduce the amount of signal spilling outside the intended coverage area. Simulcasting multiple low-power transmitters gives better coverage where it's wanted compared to a single high-power transmitter. You can fill in coverage gaps without using enough power to pick up the signal 2 counties away.
In older threads, such as Charlottesville/Albemarle simulcast, individuals were reporting reception problems with Charlottesville-Albermarle using Unidens such as the 996XT, whereas the Radio Shack PRO-106, PRO-197, and PRO-18 performed well.
krooton
Member
Hello all! I recently got a SDS100 and was doing some quick searches through the frequency range of the Richmond/Chesterfield/Henrico system and every so often a transmission could be heard then the radio would display ENC. My problem is I could clearly hear words being spoken before the ENC would be displayed, then silence.
It sounds like the radio maybe able to decrypt the audio but blocks it because it's "Encrypted".
On my old RS Pro-96, if a channel was encrypted, you could still "hear" the channel, just sounded like some alien from Star Trek.
Is there a way to make it so you can "hear" the channel on the SDS?
It sounds like the radio maybe able to decrypt the audio but blocks it because it's "Encrypted".
On my old RS Pro-96, if a channel was encrypted, you could still "hear" the channel, just sounded like some alien from Star Trek.
Is there a way to make it so you can "hear" the channel on the SDS?
Most likely, the scanner falsely believes that it is receiving encrypted audio when it's not. Perhaps the signal is weak and cuts out, causing the scanner to assign the transmission to "encrypted" status. One thing you can be sure of - it's not decrypting audio that is actually encrypted. It doesn't have the keys needed to do the decrypting.
Was the audio you heard heard "intelligible"? As fredva said scanners CAN NOT decrypt encrypted audio. You may have heard "sounds" for a moment before the scanner (or any digital receiver) decided the sound was not intelligible. The same way it does when it can't decode the "R2D2" sounds into understandable words. If you can understand what is being said then it is not encrypted.
Bill
Bill
krooton
Member
I distinctly heard intelligible words but only for a brief second. Almost as if the SDS knows that channel is tagged as Encrypted. I just want the radio to "play the audio" regardless of whether it is encrypted or not.
It may be tagged encrypted but that doesn't mean it is. It could be sometimes encrypted ( De in the database). Most digital radios mute the audio when there isn't enough signal to decode correctly. Maybe someone can tell you if your scanner can be configured to play non-decoded audio. Like everyone has said if it is encrypted it will not be understandable.
Bill
Bill
Uniden didn't make it a user-configurable option to listen to encrypted audio. There is a discussion in this thread about this: SDS100: - No Encryption notification with Uniden scanners?
- Status
Similar threads
