Indeed
To me, the RDS deviation is a bit low but this should not be a problem at all and it should not prevent the handover. We must be missing something
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| Micro MPX with RDS AF https://forums.stereotool.com/viewtopic.php?t=30709 |
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| Author: | radiohead [ Wed Jun 02, 2021 9:22 pm ] |
| Post subject: | Micro MPX with RDS AF |
Has anyone got AF (alternative frequencies) working with multiple transmitters fed over Micro MPX? (eg: handover between transmitters carrying the same service) We have a two transmitter service fed by Micro MPX over internet. We are using "Method A" and both frequencies are entered. Deviation, pilot and RDS leves are set perfectly, and confirmed by UK regulator Ofcom. The AF's show on the modulation analyser, so they are definitely being broadcast on both transmitters. RDS is working because PI is displayed on radios. There is a healthy overlap between both transmitters, yet there is no handover on any receiver that drives between the two, even when the originating TX fades to noise. An engineer whose opinion I respect told me that the two tranmitters each need to have their own freqency set first in the list - which I "think" is impossible with Micro MPX because it streams identical MPX signal to all destinations? Anyway, if this were true, surely handover would work in one direction? Two of my thoughts: 1. I'm virtually certain RF synch is not required, because I know AF works with rebroadcast relays. I'm wondering if any degree of audio/MPX Synch is necessary? That will be tricky if each transmitter is in different locations and different ISP's. 2. We are fairly heavily audio processing - I might try winding it back a bit in case that is stopping recievers resolve the pilot or something (but then again, how could they display RDS PI if that were the issue?) Any help, suggestions welcome! |
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| Author: | PaddyC [ Thu Jun 03, 2021 10:28 am ] |
| Post subject: | Re: Micro MPX with RDS AF |
Hi, I'm not too sure about your setup. From what I understand, you are using micro mpx to send the exact same MPX signal to two transmitters on two different frequencies, and there is no handover from TX1 to TX2 when you are driving. Your RDS deviation is somewhere between 2 KHz and 5 KHz. Is this correct? If this is correct, here are some questions. Is this happening with every car radio you have tested? This might sound stupid, but is the AF function enabled on your receiver? Is there a regional setting (REG) on your car radio that you could try setting on and off to see if that solves the problem? Are you transmitting both frequencies in the AF list of your RDS signal? |
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| Author: | radiohead [ Thu Jun 03, 2021 4:13 pm ] |
| Post subject: | Re: Micro MPX with RDS AF |
Yes you understand correctly. The handover is not working on any radios of various makes and models. I've never seen a switchable AF function on an RDS receiver. My one definitely does not have that - the only thing I can switch is TP. And anyway, it switches fine for every other station in the area that has multiple frequencies. Yes the RDS deviation is 2.4kHz, and yes the AF's can be seen when decoded off-air on a modulation analyser. It's a strange one.... |
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| Author: | PaddyC [ Thu Jun 03, 2021 4:21 pm ] |
| Post subject: | Re: Micro MPX with RDS AF |
Indeed To me, the RDS deviation is a bit low but this should not be a problem at all and it should not prevent the handover. We must be missing something
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| Author: | radiohead [ Thu Jun 03, 2021 7:01 pm ] |
| Post subject: | Re: Micro MPX with RDS AF |
I'm wondering if anything in the RDS AF spec needs a degree of audio/mpx synch between the transmitters to make it work. I hope not, because I can't see how that is possible when feeding over internet to different locations via differnet ISP's. |
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| Author: | hvz [ Fri Jun 04, 2021 12:40 am ] |
| Post subject: | Re: Micro MPX with RDS AF |
Hi, this definitely works on other stations - both with AF method A and B, although for method B you might need to use some special tricks. There's one station that I can receive here that has dozens of transmitters, most of which are fed though MicroMPX, and three other stations that also have multiple frequencies fed through MicroMPX, and AF switching works flawless on all of them. No need for any synchronization, even if you're playing completely different content, the receiver should still switch. So, most likely, something isn't setup correctly in the AF settings. Please verify the following: - Did you set the PI code? - Did you fill in the list of AF frequencies? If you're using AF method B, you have to broadcast the frequency that you're transmitting on multiple times, which can only be achieved for multiple frequencies by having multiple AF method B lists (which can be set if you have Advanced RDS). |
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| Author: | radiohead [ Mon Jun 07, 2021 9:52 pm ] |
| Post subject: | Re: Micro MPX with RDS AF |
It seems to have started working since I've mainly resolved the sound card speed errors and error correction.... |
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