If you're looking at getting a digital scanner, it can be difficult to tell what system support you need, especially making the decision between an SDS with its simulcast support or an older model without it.
The RRDB is a great tool, but sometimes simulcast vs. standalone is difficult to differentiate, as information could be incorrect, outdated, not submitted, or it could be a conventional channel, which generally don't have any simulcast properties listed.
If you have an analog scanner or your digital scanner isn't performing up-to-par and you suspect simulcast, there is an easy way to tell the difference.
C4FM, or standalone, has a bassy and somewhat soft sound that can occasionally sound like a diesel engine on certain systems. This is the most basic version of P25, with support across all P25 products.
Here is an example of C4FM in both conventional and trunked flavors.
If you are hearing a signal like this, about any digital scanner should work for your use case, with the exception of 700 MHz trunked on the PRO-96 and non-800 MHz trunked systems on the BC296D. If your scanner is not performing up to par and you have a C4FM signal
CQPSK has a much more higher pitch, "harsher" or "staticy" sound to it. CQPSK can be operated standalone but is primarily used for simulcast. Here is an example in conventional and trunked flavors.
Simulcasting in this case is where multiple towers transmit the same data on the same frequency at the same time in the same area. This creates an issue known as simulcast distortion, where the radio can't demodulate the signal properly because of the other towers' interference. This is very location dependent and two feet can be the difference between unreadable and just fine. Here is an example of simulcast disortion. Note how the radio switches back to FM mode due to not being able to decode the digital signal due to it.
If you can access AM mode on your scanner (most modern scanners can), you can tell the quality of your received simulcast signal easily. CQPSK exhibits a high pitched noise under AM mode, and the clearer it is, the less distortion you will have.
Here are three examples of CQPSK AM noise, undistorted, mildly distorted, and very distorted. In some extreme cases, you can even hear the "picket fencing" of the interfering signals in FM mode.
In cases of distortion, you will likely require an SDS series scanner in order to clearly receive the P25 signal. This is exacterbated in trunked systems where the radio is having to switch between the control and voice channels, which can have different propagation characteristics and can exhibit heavy distortion even with clear control channel reception. On an undistorted or clear enough signal, you can pretty much use any digital scanner, although some may be more sensitive to any distortion that may arise.
Hopefully this helped you make a better-informed decision about your new digital scanner, and of course, if you have anything to add, please feel free to comment below.
The RRDB is a great tool, but sometimes simulcast vs. standalone is difficult to differentiate, as information could be incorrect, outdated, not submitted, or it could be a conventional channel, which generally don't have any simulcast properties listed.
If you have an analog scanner or your digital scanner isn't performing up-to-par and you suspect simulcast, there is an easy way to tell the difference.
C4FM, or standalone, has a bassy and somewhat soft sound that can occasionally sound like a diesel engine on certain systems. This is the most basic version of P25, with support across all P25 products.
Here is an example of C4FM in both conventional and trunked flavors.
If you are hearing a signal like this, about any digital scanner should work for your use case, with the exception of 700 MHz trunked on the PRO-96 and non-800 MHz trunked systems on the BC296D. If your scanner is not performing up to par and you have a C4FM signal
CQPSK has a much more higher pitch, "harsher" or "staticy" sound to it. CQPSK can be operated standalone but is primarily used for simulcast. Here is an example in conventional and trunked flavors.
Simulcasting in this case is where multiple towers transmit the same data on the same frequency at the same time in the same area. This creates an issue known as simulcast distortion, where the radio can't demodulate the signal properly because of the other towers' interference. This is very location dependent and two feet can be the difference between unreadable and just fine. Here is an example of simulcast disortion. Note how the radio switches back to FM mode due to not being able to decode the digital signal due to it.
If you can access AM mode on your scanner (most modern scanners can), you can tell the quality of your received simulcast signal easily. CQPSK exhibits a high pitched noise under AM mode, and the clearer it is, the less distortion you will have.
Here are three examples of CQPSK AM noise, undistorted, mildly distorted, and very distorted. In some extreme cases, you can even hear the "picket fencing" of the interfering signals in FM mode.
In cases of distortion, you will likely require an SDS series scanner in order to clearly receive the P25 signal. This is exacterbated in trunked systems where the radio is having to switch between the control and voice channels, which can have different propagation characteristics and can exhibit heavy distortion even with clear control channel reception. On an undistorted or clear enough signal, you can pretty much use any digital scanner, although some may be more sensitive to any distortion that may arise.
Hopefully this helped you make a better-informed decision about your new digital scanner, and of course, if you have anything to add, please feel free to comment below.
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