SDRTrunk how many dongles do i need for P25 Phase 2?

[techtronicsllc]

Look at the Dmr site. Subtract the lowest freq from the highest freq and see what you get. You do not state what dongles your using.

I get that but my question is do I need a dongle for each service type? The Dmr is a single freq site. But how can I combine P25, analog and DMR site all into one stream on broadcasting and what software should I use? Seems like I need 1 for analog, 1 for DMR, and 2 for P25 to cover the freq spread.. I’m buying new dongles so plan on using the RTL SDR unless you think others are better?

 

[maus92]

My county is a mixed bag we have P25, Analog, and DMR.. the DMR is a single site... So I know I need 2 dongles for the P25 but my question is will one additional for DMR and one additional for analog work? Can these all be served on one feed to broadcastify? How does that work when you mix site types (analog, digital etc)

You do not need two dongles for P25.

 

[techtronicsllc]

You do not need two dongles for P25.

If it spreads more than 2.5MHz it does right?

 

[dave3825]

Seems like I need 1 for analog, 1 for DMR, and 2 for P25 to cover the freq spread..

I don't stream but think sdrtrunk will suit your needs. To determine total dongles needed, post a link to each site. If the Dmr and the analog are within 2 mhz of each other, you may be able to use one dongle for both. I use Airspy Mini's I bought from Itead and because 2 systems I listen to are very close in range, I am able to use 1 mini on both when running at 6 MHz. Rtl Sdr and NooElec dongles claim 2.4 usable but people have reported you actually get about 80 percent of that due to roll-off. In sdrtrunk I run my NooElec at 2.56 MHz.

 

[R0am3r]

@techtronicsllc - I believe that you will need at least one SDR for each service type you want to monitor. This assumes you are monitoring multiple services at one time. Depending on the bandwidth spread (the delta of the highest and lowest frequencies of the system), you may need more than one SDR for each service. Obviously, if you are only listening to one service at a time, you only need the basics (one or two SDRs). I believe 2.4 MHz is the maximum bandwidth for the typical RTL-SDR.

If you decide to try other hardware, you can mix and match SDRs from within SDRTrunk. I often use my SDRplay RSP1A as my tuner for a Control Channel and additional RTL-SDRs for the voice channels. This flexibility opens up lots of possibilities for Analog, DMR, MPT-1327, and P25 systems.

 

[maus92]

If it spreads more than 2.5MHz it does right?

Yes, but that is the reason, not that it's P25. Some P25 trunked systems can be monitored with one sdr because their channel spread doesn't exceed ~2 MHz. A single Airspy Mini sdr covers a roughly 6 MHz channel spread.

 

[ToddWilkinson]

I use 2 minimum, 4 max on the Armer System in MN.

 

[JasperRidley]

So sort of piggybacking on this topic, do any of you run more than 2 SDRs in SDRtrunk? I've been testing between 2 and 6 just tonsee what happens and have noticed only two actually lock at a time.

Maybe not enough traffic but some times there will be 3 or more channels locked to one SDR and 2 channels locked to the second.

 

[GTR8000]

SDRTrunk will only use the resources that it needs. If two dongles are enough to cover the channel spread, it will only use two dongles. If the site is not that busy and one dongle is enough to cover the channel spread, it won't bother with the additional dongle(s).

It all comes down to the spread between lowest and highest frequency at the site, an how many dongles are needed to cover that spread. If you have very tight channel spacing like 852.225 - 853.750, you'll never need more than a single dongle, no matter how busy the site gets. SDRTrunk can decode a theoretically infinite number of transmissions using a single dongle if all site channels fall within that dongle's bandwidth. You're only limited by CPU power at that point.

In other words, SDRTrunk does not "load balance" across multiple dongles, if that's what you're asking.

 

[JasperRidley]

SDRTrunk will only use the resources that it needs. If two dongles are enough to cover the channel spread, it will only use two dongles. If the site is not that busy and one dongle is enough to cover the channel spread, it won't bother with the additional dongle(s).

It all comes down to the spread between lowest and highest frequency at the site, an how many dongles are needed to cover that spread. If you have very tight channel spacing like 852.225 - 853.750, you'll never need more than a single dongle, no matter how busy the site gets. SDRTrunk can decode a theoretically infinite number of transmissions using a single dongle if all site channels fall within that dongle's bandwidth. You're only limited by CPU power at that point.

In other words, SDRTrunk does not "load balance" across multiple dongles, if that's what you're asking.

Thanks for the load balancing answer and explaining the bandwidth scenario. It makes perfect sense now.

I will do some testing by adding more frequencies lower in the band for the other dongles, possibly in another instance of SDR Trunk.

 

[AngWay]

@techtronicsllc - I believe that you will need at least one SDR for each service type you want to monitor. This assumes you are monitoring multiple services at one time. Depending on the bandwidth spread (the delta of the highest and lowest frequencies of the system), you may need more than one SDR for each service. Obviously, if you are only listening to one service at a time, you only need the basics (one or two SDRs). I believe 2.4 MHz is the maximum bandwidth for the typical RTL-SDR.

If you decide to try other hardware, you can mix and match SDRs from within SDRTrunk. I often use my SDRplay RSP1A as my tuner for a Control Channel and additional RTL-SDRs for the voice channels. This flexibility opens up lots of possibilities for Analog, DMR, MPT-1327, and P25 systems.

Can I please ask u a question. I have been experimenting with rtlsdr I bought 2 dongles I'm using sdrtrunk and I'm trying to listen to p25 phase 2 system the only two CC iv been able to pick up is 152.6825 and 161.800. Idk if I'm covering everything I have both frequencies put in and hit play. Idk if I need more dongles but I'm looking at getting a airspy mini to use with my 2 RTL dongles. Would this work ? And if so how would I configure it? Do I even need it? Thanks for any help u can provide I'm new to this.

 

[dave3825]

Can I please ask u a question. I have been experimenting with rtlsdr I bought 2 dongles I'm using sdrtrunk and I'm trying to listen to p25 phase 2 system the only two CC iv been able to pick up is 152.6825 and 161.800. Idk if I'm covering everything I have both frequencies put in and hit play. Idk if I need more dongles but I'm looking at getting a airspy mini to use with my 2 RTL dongles. Would this work ? And if so how would I configure it? Do I even need it? Thanks for any help u can provide I'm new to this.

If this is the site of the system your trying to scan, it spans 9.3175mhz.

2 (2)

013 (D)

Honaker

Buchanan

152.6825c

152.7125c

161.875

162.000

Since you have 2 rtl dongles, you should be able to get by, by creating 1 or 2 dummy nbfm channels. One @ 152.6975 and the other @ 161.9375. Assign one (set as preferred tuner) to one of the dongles, and assign (set as preferred tuner) the other to the second dongle. That will keep one dongle in the 150mhz range, for those 2 control channels, and the other in the 160mhz range, for the 2 voice freqs. Then start each, then start the system.

 

[AngWay]

If this is the site of the system your trying to scan, it spans 9.3175mhz.

2 (2)

013 (D)

Honaker

Buchanan

152.6825c

152.7125c

161.875

162.000

Since you have 2 rtl dongles, you should be able to get by, by creating 1 or 2 dummy nbfm channels. One @ 152.6975 and the other @ 161.9375. Assign one (set as preferred tuner) to one of the dongles, and assign (set as preferred tuner) the other to the second dongle. That will keep one dongle in the 150mhz range, for those 2 control channels, and the other in the 160mhz range, for the 2 voice freqs. Then start each, then start the system.

yes thats what i'm trying to listen to . here Virginia Statewide Agencies Radio System (STARS) Trunking System, Statewide, Virginia my county is buchanan. i just got the RR premium subscription and downloaded everything and when i chose my area and got everything ready RR put in the wrong control channel it was a alternate CC so i had to change it i found that odd. but it's crazy because the only CC that i can lock onto is the honaker one and that is farther away than the oakwood one which i am closer to so i don't understand why it's picking up the farthest away CC. also i rarely hear anything at all it's been hours since i'v heard a peep come over the air i have all this information downloaded into sdrtrunk and i thought their would be somewhat more traffic than what i'm getting. i have installed op25 and tried it but it seems to be worse than sdrtrunk i also tried unitrunker and i got as far as getting static to come through i'm thinking about trying dsd fastlane but i'm worried it won't do any better than sdrtrunk is doing right now...also i have the conventional channels downloaded to but when i try those in sdrtrunk it's just static even when i can see that their is a signal in the waterfall i just don't know i have spent 2 solid weeks at all of this and i'v learned ALOT already. i have heard about the dummy channels i will give that a try if i can figure it out. also i'll link my latest reddit post here that way u can see it and maybe help with that without me having to type it all out.

https://www.reddit.com/r/RTLSDR/comments/1d7cbt0

. and thank u so much for replying to me it's been hard to get solid info on all this so it really means alot. THANK YOU.

 

[AngWay]

If this is the site of the system your trying to scan, it spans 9.3175mhz.

2 (2)

013 (D)

Honaker

Buchanan

152.6825c

152.7125c

161.875

162.000

Since you have 2 rtl dongles, you should be able to get by, by creating 1 or 2 dummy nbfm channels. One @ 152.6975 and the other @ 161.9375. Assign one (set as preferred tuner) to one of the dongles, and assign (set as preferred tuner) the other to the second dongle. That will keep one dongle in the 150mhz range, for those 2 control channels, and the other in the 160mhz range, for the 2 voice freqs. Then start each, then start the system.

here is this what u mean by the dummy channels? oh and i am getting the oakwood CC now i realized my antenna had fallen down lol that was a first... but anyway's it's pretty much still the same as far as hearing anything. oh and when i do hear some traffic i notice it's like a hour and a half drive from where i'm at i can't make any sense of that .

 

[sunwave]

The simplest most easy way is to subtract the highest frequency from lowest frequency. For example, OKWIN, RRDB 6949 Oklahoma City site.

Top frequency: 860.9375MHz
Subtract lowest frequency: 851.0375MHz
Result 9.9MHz

Sample rate needed 9.9MHz +4MHz = 13.4MHz. We don't want the lowest and highest frequencies on the very edge is why I add 4MHz. Why 4MHz? Just a stab in the dark.

The sample rate needed is 13.4msps. The RTL-SDR dongle can safely support 2.4msps sample rate but we need 13.4msps.

So divide 13.4/2.4=5.583 round it up to 6. That means OKWIN Oklahoma City site needs a total of 6 RTL-SDR's. With 6 RTL-SDR's SDRTrunk will follow that system well. Your result will be different.

Whether or not you have enough USB current to support 6 RTL-SDR's is up to you to work out. I would use a high quality 3 or 4amp powered USB hub. One RTL-SDR draws up to 500milliamps. Depending on which variant of RTL-SDR used. Looking at 3 amps but give more headroom. Your system may require a different number of dongles.

Another thought is the out of pocket costs to listen to OKWIN. Nooelec and RTL-SDR Blog comes close in price. Let's say $35usd. I would be out of pocket a total of $210 usd. Might as well shoot for a SDRPlay RSPduo or an airspy. I hope your systems aren't this big!!

Unitrunker won't work on a APCO P25 Phase 2 system. SDRTrunk or OP25 by boatbod will.

 

[maus92]

here is this what u mean by the dummy channels? oh and i am getting the oakwood CC now i realized my antenna had fallen down lol that was a first... but anyway's it's pretty much still the same as far as hearing anything. oh and when i do hear some traffic i notice it's like a hour and a half drive from where i'm at i can't make any sense of that .

Looks like you have 2 sites from STARS programmed and they appear to be decent quality. The VSP is not super talkative on STARS, and they can roam onto LTE in some locations (which you will not always hear depending on affiliations.)

 

[AngWay]

Looks like you have 2 sites from STARS programmed and they appear to be decent quality. The VSP is not super talkative on STARS, and they can roam onto LTE in some locations (which you will not always hear depending on affiliations.)

yea i remember reading some about that...i'm testing out dsdplus fastlane now and it seems to be nice i just can't figure out how to listen to the conventional like FM FMN and DMR but i don't think there is any dmr in my area... i had fastlane p25 going earlier and i heard about 5 cops go screaming by my house then i heard there was a bad wreck down below where i live so that finally told me alot about what i was listening to.

 

[dave3825]

i just can't figure out how to listen to the conventional like FM FMN and DMR but i don't think there is any dmr in my area..

You populate the FMP24.scanlist (FMPA.scanlist if using Airspy, FMPP.scanlist if using Duo) and that lets you listen to conventional. Am, Fm Dmr etc. Only drawback is you can't do trunked and conventional at the same time, unless you have another dongle or tapped scanner.

; FMP24 Scan List
; ---------------
;
; Entries in this file are scanned when the 'S' key is pressed in FMP24
;
; Press Esc in FMP24 to exit scanner mode
;
; Lines with leading semicolons are ignored.
; Use a leading semicolon to "lock out" an entry.
; Use a leading semicolon to add comments/documentation.
;
; File processing stops if a line containing "<EOF>" is found.
; Entries after the <EOF> line are not processed.
;
;
; Line format:
;
; frequency options description
;
;
; Frequency is specified in MHz
;
;
; Options:
;
; Modulation Specifier
;
; 4 kHz bandwidth digital protocol specifiers:
;
; iDAS
; NX48
; NXDN48
; NEXEDGE48
;
; 7.6 kHz bandwidth digital protocol specifiers:
;
; Dstar
; D-Star
; DMR
; TRBO
; Cap+
; Con+
; TIII
; XPT
;
; 9.5 kHz bandwidth digital protocol specifiers:
;
; Fusion
; NX96
; NXDN96
; NEXEDGE96
; P25
;
; 12.5 kHz bandwidth digital protocol specifiers:
;
; PV
; ProVoice
;
; Analog modulation specifiers:
;
; AM (AM demodulation for airband)
;
; Anything else, such as "FM" or "Analog" or nothing
; is assumed to be FM modulated analog and defaults to 12.5 kHz bandwidth
;
;
; Bandwidth Specifier
;
; Overrides default bandwidth
;
; Format: BW=<kHz>
;
; Valid bandwidth values are 4, 7.6, 9.5, 12.5 and 22
;
;
; Delay Specifier
;
; Keeps FMP24 on a channel / delays resumption of scanning
; for the specified amount of time after a valid signal ends
;
; Format: DELAY=<seconds>
;
;
; Description
;
; User-supplied channel name/description
;
;
; Sample scan list:

118.3 AM BW=12.5 DELAY=2.5 Miami Tower

145.17 DMR DELAY=1.5 N2GKG

162.4 FM WX

454.35 NX48 Acme Inc.

163.8125 P25 BW=12.5 DELAY=5 Feds

<EOF>

; any entries after <EOF> line are not scanned

 

[AngWay]

You populate the FMP24.scanlist (FMPA.scanlist if using Airspy, FMPP.scanlist if using Duo) and that lets you listen to conventional. Am, Fm Dmr etc. Only drawback is you can't do trunked and conventional at the same time, unless you have another dongle or tapped scanner.

did i do these entries right ? and now that i did that do i just run dsdplus FL as i normally would?

; FMP24 Scan List
; ---------------
;
; Entries in this file are scanned when the 'S' key is pressed in FMP24
;
; Press Esc in FMP24 to exit scanner mode
;
; Lines with leading semicolons are ignored.
; Use a leading semicolon to "lock out" an entry.
; Use a leading semicolon to add comments/documentation.
;
; File processing stops if a line containing "<EOF>" is found.
; Entries after the <EOF> line are not processed.
;
;
; Line format:
;
; frequency options description
;
;
; Frequency is specified in MHz
;
;
; Options:
;
; Modulation Specifier
;
; 4 kHz bandwidth digital protocol specifiers:
;
; iDAS
; NX48
; NXDN48
; NEXEDGE48
;
; 7.6 kHz bandwidth digital protocol specifiers:
;
; Dstar
; D-Star
; DMR
; TRBO
; Cap+
; Con+
; TIII
; XPT
;
; 9.5 kHz bandwidth digital protocol specifiers:
;
; Fusion
; NX96
; NXDN96
; NEXEDGE96
; P25
;
; 12.5 kHz bandwidth digital protocol specifiers:
;
; PV
; ProVoice
;
; Analog modulation specifiers:
;
; AM (AM demodulation for airband)
;
; Anything else, such as "FM" or "Analog" or nothing
; is assumed to be FM modulated analog and defaults to 12.5 kHz bandwidth
;
;
; Bandwidth Specifier
;
; Overrides default bandwidth
;
; Format: BW=<kHz>
;
; Valid bandwidth values are 4, 7.6, 9.5, 12.5 and 22
;
;
; Delay Specifier
;
; Keeps FMP24 on a channel / delays resumption of scanning
; for the specified amount of time after a valid signal ends
;
; Format: DELAY=<seconds>
;
;
; Description
;
; User-supplied channel name/description
;
;
; Sample scan list:

155.220 FMN BW=12.5 DELAY=2.5 SlateCrkMRS

460.6125 FMN BW=12.5 DELAY=2.5 SlateCrkVFDL

154.325 FMN BW=12.5 DELAY=2.5 SlateCrkVFD

463.700 FMN DELAY=1.5 Grundy PD

159.150 FM BW=12.5 DELAY=2.5 Sheriff

154.3775 NXDN48E BW=12.5 DELAY=2.5 Oakwood Fire Department

154.190 NXDN48 BW=12.5 DELAY=2.5 Grundy Volunteer Fire Department

151.745 NXDN48 BW=12.5 DELAY=2.5 Prater Fire/Rescue Dispatch

155.160 FM BW=12.5 DELAY=2.5 BuchCoEMS

152.285 FMN BW=12.5 DELAY=2.5 CouncFD Disp

151.925 FMN BW=12.5 DELAY=2.5 Buch F/E KnM

151.520 FMN BW=12.5 DELAY=2.5 Buch F/E En

454.35 NX48 Acme Inc.

163.8125 P25 BW=12.5 DELAY=5 Feds

<EOF>

; any entries after <EOF> line are not scanned

 

[dave3825]

did i do these entries right ?

I do not believe there is a specifier for FMN

and now that i did that do i just run dsdplus FL as i normally would?

Entries in this file are scanned when the 'S' key is pressed in FMP24

154.3775 NXDN48E BW=12.5 DELAY=2.5 Oakwood Fire Department

NXDN48E is not a valid specifier. The E indicates the freq is listed as full time encrypted.