Re: [App_rpt-users] Simulcasting with RTCM/voter
Thanks for your thoughts Jesse and Tim. Ah, perhaps that was my issue, I was setting the delay, doing a 99 to save to EEPROM but not rebooting. Perhaps I need to try this next. Basically the test you have described Jesse is what I am doing at home. I believe from what I have read and understand from Joe's messages, Tim that some error in the launch delay is OK at voice. I read somewhere over 110uS it starts to become a problem. I certainly can get away with no PL encoding on the transmitter, I was merely using it as a means of double checking my audio phasing. Voice sounds OK, depending on my frequency offset. It does have a level of distortion however - again maybe due to the launch delay not being set correctly. I suppose a semi bonus is that at 6 metres, normal propagation effects cause noise, crackles, phase cancellations etc so it may just all sound natural anyway. Sporadic E openings will be interesting though :). Currently my main site has a significant overlap of my planned secondary site. I may need to reconsider this to reduce the overlap. 73 Hayden
The delta should be less than 83uS for voice is what I read. Digital (i.e. P25) needs to be even less, not that that's what your dealing with here. Of course the signal strength comes into play as well. The overlap areas are defined as areas where the signal is within 10dB. The Radio Mobile program can accept these figures and plot the simulcast interference. It takes some doing to figure out but well worth the effort. I've found it amazingly accurate. I might have an example plot to share if anyone is interested. The DAC problem is related to audio phase not launch delay. So the audio will sound bad even with the proper launch delay. On Mon, Mar 13, 2017 at 8:10 PM, Hayden Honeywood <haydenph91@gmail.com> wrote:
Thanks for your thoughts Jesse and Tim.
Ah, perhaps that was my issue, I was setting the delay, doing a 99 to save to EEPROM but not rebooting. Perhaps I need to try this next. Basically the test you have described Jesse is what I am doing at home.
I believe from what I have read and understand from Joe's messages, Tim that some error in the launch delay is OK at voice. I read somewhere over 110uS it starts to become a problem.
I certainly can get away with no PL encoding on the transmitter, I was merely using it as a means of double checking my audio phasing. Voice sounds OK, depending on my frequency offset. It does have a level of distortion however - again maybe due to the launch delay not being set correctly. I suppose a semi bonus is that at 6 metres, normal propagation effects cause noise, crackles, phase cancellations etc so it may just all sound natural anyway. Sporadic E openings will be interesting though :).
Currently my main site has a significant overlap of my planned secondary site. I may need to reconsider this to reduce the overlap.
73 Hayden
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-- -- Tim
"The DAC problem is related to audio phase not launch delay. So the audio will sound bad even with the proper launch delay." I am just shooting from the hip on this, but would it be possible to insert a preamble into the simulcast stream that the DAC's would each reproduce and some additional circuitry or code could monitor and use to correct the audio phase at each RTCM? I am sure I am oversimplifying, but, thoughts? Joe On 3/14/2017 10:33 AM, Tim Sawyer wrote:
The delta should be less than 83uS for voice is what I read. Digital (i.e. P25) needs to be even less, not that that's what your dealing with here. Of course the signal strength comes into play as well. The overlap areas are defined as areas where the signal is within 10dB.
The Radio Mobile program can accept these figures and plot the simulcast interference. It takes some doing to figure out but well worth the effort. I've found it amazingly accurate. I might have an example plot to share if anyone is interested.
The DAC problem is related to audio phase not launch delay. So the audio will sound bad even with the proper launch delay.
On Mon, Mar 13, 2017 at 8:10 PM, Hayden Honeywood <haydenph91@gmail.com <mailto:haydenph91@gmail.com>> wrote:
Thanks for your thoughts Jesse and Tim.
Ah, perhaps that was my issue, I was setting the delay, doing a 99 to save to EEPROM but not rebooting. Perhaps I need to try this next. Basically the test you have described Jesse is what I am doing at home.
I believe from what I have read and understand from Joe's messages, Tim that some error in the launch delay is OK at voice. I read somewhere over 110uS it starts to become a problem.
I certainly can get away with no PL encoding on the transmitter, I was merely using it as a means of double checking my audio phasing. Voice sounds OK, depending on my frequency offset. It does have a level of distortion however - again maybe due to the launch delay not being set correctly. I suppose a semi bonus is that at 6 metres, normal propagation effects cause noise, crackles, phase cancellations etc so it may just all sound natural anyway. Sporadic E openings will be interesting though :).
Currently my main site has a significant overlap of my planned secondary site. I may need to reconsider this to reduce the overlap.
73 Hayden
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-- -- Tim
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-- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
any more progress on this? On 3/14/2017 1:54 PM, Joe Leikhim wrote:
"The DAC problem is related to audio phase not launch delay. So the audio will sound bad even with the proper launch delay."
I am just shooting from the hip on this, but would it be possible to insert a preamble into the simulcast stream that the DAC's would each reproduce and some additional circuitry or code could monitor and use to correct the audio phase at each RTCM?
I am sure I am oversimplifying, but, thoughts?
Joe
On 3/14/2017 10:33 AM, Tim Sawyer wrote:
The delta should be less than 83uS for voice is what I read. Digital (i.e. P25) needs to be even less, not that that's what your dealing with here. Of course the signal strength comes into play as well. The overlap areas are defined as areas where the signal is within 10dB.
The Radio Mobile program can accept these figures and plot the simulcast interference. It takes some doing to figure out but well worth the effort. I've found it amazingly accurate. I might have an example plot to share if anyone is interested.
The DAC problem is related to audio phase not launch delay. So the audio will sound bad even with the proper launch delay.
On Mon, Mar 13, 2017 at 8:10 PM, Hayden Honeywood <haydenph91@gmail.com <mailto:haydenph91@gmail.com>> wrote:
Thanks for your thoughts Jesse and Tim.
Ah, perhaps that was my issue, I was setting the delay, doing a 99 to save to EEPROM but not rebooting. Perhaps I need to try this next. Basically the test you have described Jesse is what I am doing at home.
I believe from what I have read and understand from Joe's messages, Tim that some error in the launch delay is OK at voice. I read somewhere over 110uS it starts to become a problem.
I certainly can get away with no PL encoding on the transmitter, I was merely using it as a means of double checking my audio phasing. Voice sounds OK, depending on my frequency offset. It does have a level of distortion however - again maybe due to the launch delay not being set correctly. I suppose a semi bonus is that at 6 metres, normal propagation effects cause noise, crackles, phase cancellations etc so it may just all sound natural anyway. Sporadic E openings will be interesting though :).
Currently my main site has a significant overlap of my planned secondary site. I may need to reconsider this to reduce the overlap.
73 Hayden
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To unsubscribe from this list please visit http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users <http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users> and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- -- Tim
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-- Joe Leikhim
Leikhim and Associates
Communications Consultants
Oviedo, Florida
JLeikhim@Leikhim.com
407-982-0446
WWW.LEIKHIM.COM
_______________________________________________ App_rpt-users mailing list App_rpt-users@lists.allstarlink.org http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users
To unsubscribe from this list please visit http://lists.allstarlink.org/cgi-bin/mailman/listinfo/app_rpt-users and scroll down to the bottom of the page. Enter your email address and press the "Unsubscribe or edit options button" You do not need a password to unsubscribe, you can do it via email confirmation. If you have trouble unsubscribing, please send a message to the list detailing the problem.
-- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida JLeikhim@Leikhim.com 407-982-0446 WWW.LEIKHIM.COM
participants (3)
-
Hayden Honeywood -
Joe Leikhim -
Tim Sawyer