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

AngWay

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ok so your saying don't use FMN but use FM? thats how it was on radio reference . and what NXDN48 do i use that exactly when there isn't a E
 

AngWay

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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.
ok i have 2 rtlsdr dongles right now and the system i am trying to listen to is in the attached photo below they are the honaker, oakwood, elkin's branch. can you look at that and tell me if 2 dongles will cover it or do i need to get a airspy mini to compensate. i greatly appreciate it.
 

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dave3825

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ok so your saying don't use FMN but use FM?
I am saying there is not a FMN specifier listed in the options.
; Anything else, such as "FM" or "Analog" or nothing
; is assumed to be FM modulated analog and defaults to 12.5 kHz bandwidth

thats how it was on radio reference
Radio Reference and DSDPlus are not the same.
what NXDN48 do i use that exactly when there isn't a E

; 4 kHz bandwidth digital protocol specifiers:
;
; iDAS
; NX48
; NXDN48
; NEXEDGE48



ok i have 2 rtlsdr dongles right now and the system i am trying to listen to is in the attached photo below they are the honaker, oakwood, elkin's branch. can you look at that and tell me if 2 dongles will cover it or do i need to get a airspy mini to compensate. i greatly appreciate it.
You are all over the place. And Sdrtrunk was answered already. The first 2 sites are a mix of 150 and 160 mhz freqs. You need to set up a dummy NBFM channel for each range. Did you do that?

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.

Since the 3rd site is 160 range, it should work off of the dongle you set for 160

2 (2)013 (D)HonakerBuchanan152.6825c152.7125c161.875162.000
2 (2)017 (11)OakwoodBuchanan152.8175c161.800c
2 (2)027 (1B)Elkin's BranchBuchanan161.900c161.9375c161.950c

In the end, you should have 2 dummy channels and 3 sites
 

AngWay

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I am saying there is not a FMN specifier listed in the options.



Radio Reference and DSDPlus are not the same.







You are all over the place. And Sdrtrunk was answered already. The first 2 sites are a mix of 150 and 160 mhz freqs. You need to set up a dummy NBFM channel for each range. Did you do that?



Since the 3rd site is 160 range, it should work off of the dongle you set for 160

2 (2)013 (D)HonakerBuchanan152.6825c152.7125c161.875162.000
2 (2)017 (11)OakwoodBuchanan152.8175c161.800c
2 (2)027 (1B)Elkin's BranchBuchanan161.900c161.9375c161.950c

In the end, you should have 2 dummy channels and 3 sites
that is what i don't understand this is all brand new to me so i appoligize for the questions. and i'm not the best at math when it comes to figuring out the dummy channels do i set the first dongle to a control channel 152.6825c and the second dongle to control channel 161.800 and then create two dummy channels? or or just set one dongle to a control channel and create two dummy channels? u seem to be very much more knowledgeable at this than me, i just started this a week ago how would you set it up if u was setting up with the exact setup i have? ...and i have a question about the bandwidth i see people that use sdrtrunk with 2 dongles and they are listening to like 851.9873 and 853.8301 and from what i have learned thats a 2mhz bandwidth but mine are from 152 to 162 so wouldn't i need more than 4.8 mhz that two dongles provide?. i won't bother u no more about it i'm just trying to figure those two things out in layman terms i guess u could say.
 

AngWay

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I am saying there is not a FMN specifier listed in the options.



Radio Reference and DSDPlus are not the same.







You are all over the place. And Sdrtrunk was answered already. The first 2 sites are a mix of 150 and 160 mhz freqs. You need to set up a dummy NBFM channel for each range. Did you do that?



Since the 3rd site is 160 range, it should work off of the dongle you set for 160

2 (2)013 (D)HonakerBuchanan152.6825c152.7125c161.875162.000
2 (2)017 (11)OakwoodBuchanan152.8175c161.800c
2 (2)027 (1B)Elkin's BranchBuchanan161.900c161.9375c161.950c

In the end, you should have 2 dummy channels and 3 sites
here is what i have setup what do u think?. also the only control channels i can lock onto is 152.6825 and 161.800 i only am using the 152.6825 there do i not worry about the 161.800 or do i create another channel and lock onto it to. PS i had to turn the squelch threshold down from -78 to -57 on the dummy channels to stop the static is that ok?
 

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dave3825

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You have the NBFM channels and only one of the three sites you asked about. Start the other two sites and check your tuners tab and verify that one dongle is 150 and the other 160. Like mine, for 700 and 800

1717787833728.png
 

AngWay

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You have the NBFM channels and only one of the three sites you asked about. Start the other two sites and check your tuners tab and verify that one dongle is 150 and the other 160. Like mine, for 700 and 800

View attachment 163565
ok here is what i got. the elkins branch CC won't lock on none of them will so idk about it but i have the honaker and oakwood setup is this what ur saying. i see u are using 2 airspy's i'm only using 2 RTL-SDR V4 dongles. thats why i was asking if 2 of those would be enough. but i am locked onto the 152 and 160 CC with the dummy channels set to what u told me.
 

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AngWay

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Can you post a screenshot of each dongle showing the spectrum? Like this?

View attachment 163572

View attachment 163573
ok yeah but when i right click on the waterfall it asks me which dongle i want to show so idk if that matter's i'll post the waterfall each dongle. the first two pictures is the waterfall set on dongle 2 and the second two pictures is dongle 1.
 

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dave3825

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Wanted to see the measured ppm, are they close to 0 ppm? Your noise floor looks nice and low, like it should. What are you using for antennas?
 

AngWay

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Wanted to see the measured ppm, are they close to 0 ppm? Your noise floor looks nice and low, like it should. What are you using for antennas?
my antennas are just the one that comes in the RTL-SDR bundle a dipole . the ppm is different per dongle one is -2.201 and the other is -1.527 they are set to auto adjust. so like i said i noticed u are using airspy's and i'm using just 2 rtl-sdr v4 dongles am i good on that because i am looking at buying a airspy to go with them but i really don't want to spend that much if i really don't need it. i see ur frequency is between 852 and 771 and u are using 2 airspy's which is more than enough and mine is 152 to 161 and i know two rtl-sdr's don't cover that much
 

dave3825

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the ppm is different per dongle one is -2.201 and the other is -1.527 they are set to auto adjust.
As long as they are at or close to zero.

1717808467258.png

i noticed u are using airspy's and i'm using just 2 rtl-sdr v4 dongles am i good on that

i see ur frequency is between 852 and 771 and u are using 2 airspy's which is more than enough and mine is 152 to 161 and i know two rtl-sdr's don't cover that much

My situation is different than yours. I am scanning 2 systems, 3 sites total with 2 airspy mini's. I was using 2 NooElec @2.56 and would miss calls.

1717807714499.png

1 mini is scanning two 700mhz sites (that are on different systems) that span just over 4mhz total.

The second mini is scanning the 800mhz site that spans 2.4375mhz. The typical dongle does about 2.4 mhz. The airspy mini claims 6mhz. Some say you get about 5mhz. Sdr# limits the mini to 4.8mhz. and FMPA limits it to 2.4mhz I believe.

With the set up you are doing, 2 of the sites in your county are using both 150 and 160 mhz freqs. The third site is using just 160. Even if you get an airspy r2, that claims 10 MHz and you end with something like 9. Take the highest freq and minus the lowest freq on your sites and you get 9.3175 mhz.

Theoretically, using the 2 rtl sdr dongles you have should work with the dummy channels. You could try raising your gain to get a lock on the control channels and or move the antenna's where they might get a stronger signal. Make sure you have all freqs listed in each site programmed into sdrtrunk.

I recently acquired a HackRf and that does 20mhz. Pretty sure something's up with it. I have read they are a little week but this one is almost deaf.
 

AngWay

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As long as they are at or close to zero.

View attachment 163585





My situation is different than yours. I am scanning 2 systems, 3 sites total with 2 airspy mini's. I was using 2 NooElec @2.56 and would miss calls.

View attachment 163584

1 mini is scanning two 700mhz sites (that are on different systems) that span just over 4mhz total.

The second mini is scanning the 800mhz site that spans 2.4375mhz. The typical dongle does about 2.4 mhz. The airspy mini claims 6mhz. Some say you get about 5mhz. Sdr# limits the mini to 4.8mhz. and FMPA limits it to 2.4mhz I believe.

With the set up you are doing, 2 of the sites in your county are using both 150 and 160 mhz freqs. The third site is using just 160. Even if you get an airspy r2, that claims 10 MHz and you end with something like 9. Take the highest freq and minus the lowest freq on your sites and you get 9.3175 mhz.

Theoretically, using the 2 rtl sdr dongles you have should work with the dummy channels. You could try raising your gain to get a lock on the control channels and or move the antenna's where they might get a stronger signal. Make sure you have all freqs listed in each site programmed into sdrtrunk.

I recently acquired a HackRf and that does 20mhz. Pretty sure something's up with it. I have read they are a little week but this one is almost deaf.
ok the 3rd site i don't get anything so i'm only using the honaker and oakwood sites. i made the dummy channels i'll add a pic showing my setup right now tell me if those dummy channels are correct. anyway's thank you so much for being patient with all of this u have really helped me ALOT! i'm so new to all this but i have always loved radios ever since my grandpa use to listen to police on his analog scanner. those were the days... i was looking at a radio shack pro 668 earlier that someone wanted to sell for $200 but i don't know if that would be better than what i have right now. i may still get a airspy mini and use it with my 2 dongles maybe set the CC on the airspy and let the rtl's scan i just would hate to spend the money and not see any improvement. anyway's thank you so muuch.
 

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dave3825

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tell me if those dummy channels are correct.

To me they look good.


i may still get a airspy mini and use it with my 2 dongles maybe set the CC on the airspy and let the rtl's scan i just would hate to spend the money and not see any improvement. anyway's thank you so muuch.


The Honaker site lists both cc's as 152.xxx. The Oakwood site has one cc 152.xxx and one cc 161.xxx, a span of 8.9825mhz. The mini will not cover that.
 

AngWay

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To me they look good.





The Honaker site lists both cc's as 152.xxx. The Oakwood site has one cc 152.xxx and one cc 161.xxx, a span of 8.9825mhz. The mini will not cover that.
ok so i bought a extra RTL-SDR would i set 2 dongles to a control channel and let the third dongle help out?
 

AngWay

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My opinion and it may differ from others however I think you need at least 2. One to monitor the control channel and one for voice channels. I have 3 in my set up and I have seen 1 dongle record 6 talk groups and rarely use the 3rd dongle BUT it does use the 3rd one on occasion.
i have been using 2 dongles for awhile and i can only pick up two control channels where i'm at one is 152.6825 and the other is 161.800. i just ordered a 3rd dongle to see if it will improve anything. do u only lock onto one CC at a time and let the other two roam free? i'm mixed between using 2 dongles to lock onto each CC and letting the 3rd dongle free or just locking onto one CC channel and letting two dongles roam free. what has been your experience so far using 3 dongles
 

dave3825

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i can only pick up two control channels where i'm at one is 152.6825 and the other is 161.800.


do u only lock onto one CC at a time and let the other two roam free?
To follow a site, you need to be locked on its control channel.

2 (2)013 (D)HonakerBuchanan152.6825c152.7125c161.875162.000
2 (2)017 (11)OakwoodBuchanan152.8175c161.800c

If dongle 1 is tuned to dummy channel of 152.6975, it should lock on the cc and reach any voice channels within 2 mhz of its centerpoint (152.6975).
If dongle 2 is tuned to dummy channel of 161.9375, it should lock on the cc and reach any voice channels within 2 mhz of its center point (161.9375).

What do you have the sample rate set at on each tuner?
 

AngWay

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To follow a site, you need to be locked on its control channel.

2 (2)013 (D)HonakerBuchanan152.6825c152.7125c161.875162.000
2 (2)017 (11)OakwoodBuchanan152.8175c161.800c

If dongle 1 is tuned to dummy channel of 152.6975, it should lock on the cc and reach any voice channels within 2 mhz of its centerpoint (152.6975).
If dongle 2 is tuned to dummy channel of 161.9375, it should lock on the cc and reach any voice channels within 2 mhz of its center point (161.9375).

What do you have the sample rate set at on each tuner?
ok i can understand that now.

i just got my 3rd dongle today and added it to the setup is their anything i need to do with it or set it to?

my sample rate is 2.400mhz i have tried setting it to 2.560 but it wants to drop the CC, sometimes it will do good at 2.560 but sometimes it won't so i just leave it on 2.400.

i am in the process of putting a J Pole antenna on the roof of my house i already have the antenna and i just bought a LNA and a CATV splitter so maybe that will help the signal and i can run 2.560 what is your opinion on that?.

oh and the dummy channels are set to NBFM but i was reading another post on here and it said to use p25 to set dummy channels i'll add a pic about that.
Thanks a lot!.
 

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maus92

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I would make sure to assign unique serial numbers to each dongle. Also, for the systems / sites you have described, you only need two dongles.
 

AngWay

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I would make sure to assign unique serial numbers to each dongle. Also, for the systems / sites you have described, you only need two dongles.
i have assigned unique serial numbers already. i have noticed some more traffic after adding the 3rd dongle either way it's there if it's needed. now i just need to make sure i set my antenna up correct..based on what i told u do u think that will be ok? as far as how to set it up?
 
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