• To anyone looking to acquire commercial radio programming software:

    Please do not make requests for copies of radio programming software which is sold (or was sold) by the manufacturer for any monetary value. All requests will be deleted and a forum infraction issued. Making a request such as this is attempting to engage in software piracy and this forum cannot be involved or associated with this activity. The same goes for any private transaction via Private Message. Even if you attempt to engage in this activity in PM's we will still enforce the forum rules. Your PM's are not private and the administration has the right to read them if there's a hint to criminal activity.

    If you are having trouble legally obtaining software please state so. We do not want any hurt feelings when your vague post is mistaken for a free request. It is YOUR responsibility to properly word your request.

    To obtain Motorola software see the Sticky in the Motorola forum.

    The various other vendors often permit their dealers to sell the software online (i.e., Kenwood). Please use Google or some other search engine to find a dealer that sells the software. Typically each series or individual radio requires its own software package. Often the Kenwood software is less than $100 so don't be a cheapskate; just purchase it.

    For M/A Com/Harris/GE, etc: there are two software packages that program all current and past radios. One package is for conventional programming and the other for trunked programming. The trunked package is in upwards of $2,500. The conventional package is more reasonable though is still several hundred dollars. The benefit is you do not need multiple versions for each radio (unlike Motorola).

    This is a large and very visible forum. We cannot jeopardize the ability to provide the RadioReference services by allowing this activity to occur. Please respect this.

Control Channel Modulation

chrismol1

P25 TruCking!
Joined
Mar 15, 2008
Messages
1,148
After reading the postings in a state forum on control channel modulation regarding trunking sites astro25 9600 control channel modulation C4FM vs CQPSK. I understand that simulcast sites are CQPSK(LSM) and ASR Astro Standalone Repeater fill in sites typically do not use simulcast? and are typically of C4FM modulation. How does the subscriber handle this? I've seen astro25 smartzone systems with sometimes neighbors as these standalone sites. Does it automatically switch modulation? Will a subscriber system programmed in CF4M see a decreased performance on a switch to a CQPSK neighbor site or a CQPSK programmed system see decreased performance switched to a C4FM neighbor site? Does the radio figure it out itself?

I've noticed in Astro25 XTS/XTL CPS it states
Digital Modulator Type (Trunking System, Digital)
C4FM: Compatible 4-Level Frequency Modulation for non-simulcast operation
CQPSK: Compatible Quadrature Phase Shift Keying for narrowband simulcast operation.
Note: This function is available to radio models equipped with CAI (Common Air Interface) Digital Operation.
WIDE: Wideband simulcast operation
Note: Cannot be chosen if a Channel Bandwidth of 12.5 kHz is selected.
The factory default is "CQPSK" forASTRO25 Trunking
The factory default is "C4FM" for Type II Trunking
But then APX CPS it is revised
Digital Modulator Type (Trunking System, Digital)
C4FM
( Factory Default for Type II Trunking )
Continuos 4-Level Frequency Modulation for non-simulcast operation.
CQPSK
( Factory Default for ASTRO 25 Trunking )
Compatible Quadrature Phase Shift Keying for narrowband simulcast operation and non-simulcast operation.
DotYellow.png This selection is only available to radio models equipped with CAI (Common Air Interface) Digital Operation.
 

mrsvensven

Member
Joined
Jul 27, 2006
Messages
164
A subscriber set to C4FM will work very poorly when decoding CQPSK transmissions.

A subscriber set to CQPSK seems to receive either CQPSK or C4FM just fine.

On Motorola radios, the C4FM/CQPSK setting is per trunk system. So generally it will be set to CQPSK even when operating on ASR sites.
 

GTR8000

NY/NJ Database Guy
Database Admin
Joined
Oct 4, 2007
Messages
15,412
Location
BEE00
and ASR Astro Standalone Repeater fill in sites typically do not use simulcast?
ASR sites are not simulcast by their very nature of being standalone, so I'm a bit confused by this question.

The default Digital Modulator Type for P25 systems in both ASTRO 25 and APX CPS is CQPSK. That setting works just fine on ASR (C4FM) or IP Simulcast (LSM/QPSK) sites.

There are many examples of ASTRO 25 systems that feature a mixture of IP Simulcast cells and ASR sites, and so the subscribers are expected to perform just as well when roaming between them.

Also note that ASR are not exactly "fill in" sites as the old SmartZone IntelliRepeaters were. Many ASR sites on modern P25 systems are full fledged sites in areas where there is no need for a full simulcast cell. This is particularly true with wide-area systems, where it may not be possible to license the same frequencies over a wide enough area to create a simulcast cell.
 

mrsvensven

Member
Joined
Jul 27, 2006
Messages
164
On conventional channels, you can change the setting per channel. I have spent quite a lot of effort trying to figure out if my neighboring systems are C4FM or CQPSK so I can set my codeplug to the appropriate value.

All this raises the question- Why is it even selectable? Why not just have the radio always in CQPSK mode if it works fine with either modulation type? I went as far as to ask this question to one of the engineers on the P25 standards body and the only response I got was "I guess nobody has thought about it before"
 

KevinC

Big Dog...celebrating 10 years of abuse!
Super Moderator
Joined
Jan 7, 2001
Messages
11,335
Location
Home
On conventional channels, you can change the setting per channel. I have spent quite a lot of effort trying to figure out if my neighboring systems are C4FM or CQPSK so I can set my codeplug to the appropriate value.

All this raises the question- Why is it even selectable? Why not just have the radio always in CQPSK mode if it works fine with either modulation type? I went as far as to ask this question to one of the engineers on the P25 standards body and the only response I got was "I guess nobody has thought about it before"

You lose about 1.2 dB of outbound coverage when using LSM/CQPSK. But the recommendation is to set it to LSM/CQPSK unless you are severely outbound limited.
 

BMDaug

I am licensed…
Premium Subscriber
Joined
Jan 18, 2022
Messages
1,102
Location
Central Colorado, USA
With a Harris radio, you can’t set the SU modulation… You can check the Linear Simulcast box (which does not determine a modulation as simulcasts can be either), and if you check that box, you can then optionally check the Adaptive Filter box, which according to the manual, should only be used if the simulcast CCs are CQPSK. Maybe a Harris SU simply always matches the CC modulation? I have no way to test this hypothesis…

-B
 

chrismol1

P25 TruCking!
Joined
Mar 15, 2008
Messages
1,148
Okay, I have many not quite understandable questions. I use Motorola in NAS. I've use TX Inhibit and moved over to the trunked talkgroup to check RSSI, where I was met with no signal and Out of Range message in CQPSK which fixed it self when I re-programmed that systems site/(with neighbors on simulcast cells in db)...to C4FM where I got a signal meter on that single cell site and reasonable RSSI. I'm wondering if an actual subscriber will ignore the NAS results I received when roaming between that single site and actual simulcast site
 

iowajm780

Member
Joined
Sep 12, 2021
Messages
177
Okay, I have many not quite understandable questions. I use Motorola in NAS. I've use TX Inhibit and moved over to the trunked talkgroup to check RSSI, where I was met with no signal and Out of Range message in CQPSK which fixed it self when I re-programmed that systems site/(with neighbors on simulcast cells in db)...to C4FM where I got a signal meter on that single cell site and reasonable RSSI. I'm wondering if an actual subscriber will ignore the NAS results I received when roaming between that single site and actual simulcast site
You did what?.
 
Top