I'm still using a mix of Palomar Telecom, ACC and RLC units.

Something wrong with the CAT? Why are you upgrading?

I will say that I've had some conversations with the SCOM folks

Before anyone says anything, the ACC units are on standalones.

Best,

Chris
--
Chris Baldwin, CETSr. (KF6AJM)
Trustee - MetroNET Cal. Intertie (KB3PX)

On Oct 27, 2022, at 9:09 AM, Allan Overcast via groups.io <allanovercast@...> wrote:

?LinkComm controllers were moved to Audio Test Solutions, Inc (ATSI) several years ago.? So ATSI RLC controllers are the same as the LinkComm, I just wanted a separate company for the amateur product line.
Allan Overcast
President and CEO
ATSI\LinkComm

Morning Kevin,et al,

I agree for the initialing radio that pre-emphasis before clipping is the way to go. My thoughts are that if it is done again, there are loss of too many highs if it is desired to add a little compression to the repeater. Perhaps I am wrong, but by a little bit of clipping ( audio compression using clipping) in the repeater done at a flat audio point, there will not be more loss of highs in proportion to mid and low frequencies and direct audio will sound the same as repeat audio just with a bit more "umph". By the way , note that with the Micor and SyntorX9000 audio curves that if there was no clipping, the low pass knee could be as low as 2500cps and repeat would sound identical to direct, so going to 3000cps on thru-put just adds undesirable transmit bandwidth with no range gain, and possibly more squelch tail noise vs audio peaks.

John

On 10/27/2022 9:35 AM Kevin Custer <kuggie@...> wrote:

John mentions the process on how he'd implement one audio processing product that is "out there".? I purposely didn't reference the AP-50 in my earlier post so people wouldn't consider the post a sales opportunity.

John says that he'd apply clipping to audio that's spectrally flat.? I wouldn't - and here's why.

Everyone knows the energy in the upper part of the frequencies for voice communications are considerably lower than the lower ones.? Clipping voice audio that's spectrally flat then doesn't apply as much processing to these upper frequencies that are lower in level.? I prefer to pre-emphasize the audio prior to clipping as it sounds better to me.? If you look at some of the exciters that have been used to build repeaters over the years, many of them, including the Motorola MICOR also pre-emphasize the audio before its application to the clipping stage.? In fact - some phase modulated exciters will pre-emphasize - clip - filter - de-emphasize and then feed the PM which ultimately pre-emphasizes the resulting audio.? Evidentially Motorola thought this sounded better too, otherwise they would not have gone through all of the pre - de machinations.? Motorola's FM exciters in this line simply deleted the de-emphasis stage so the resulting pre-emphasized - clipped - filtered audio was applied to the FM modulator.

The AP-50 is designed to allow the builder to choose which method they feel is best for them.? This is very casually mentioned in the AP-50's data sheet.

Like Bob Dengler said - the challenge is the overall headroom required.? Thankfully - with 12V applied to the output op-amp stage the circuit (just) makes it without adding clipping past the LPF, which would be terrible and defeat the protection the processing is supposed to provide in the first place.

Kevin W3KKC


On 10/26/2022 9:45 PM, John wrote:

This ongoing discussion on setting repeater audio stimulated me to check out Kevin's AP-50 which had been sitting in the workshop for years without being put to use. There has been absolutely no collusion or discussion with Kevin . Years ago I had made the enclosed graph on first a SyntorX9000 mic input audio vs deviation from 50-5000cps, and then as comparison a phase modulated Micor and then a FM?? modulated Micor, all on 6 meters. It is not quite apples vs apples because the modulation limiter was set for max dev at 1000cps of a bit more than +-6Kz on the X9000, unknown level on the phase modulated Micor, and +-9KHz? at 1000cps on the FM Micor. As you can see, the X9000 had an exactly even 6dB/ octave pre-emphasis from 50 to 2250 cps and a superior roll off above 3KHz. (could make a good sounding repeater). The AP-50 did not have the pre-emphasis option? hooked up before the clipper so you can see how flat it is between 250 and 3000cps, but wow what a comparatively steep roll off above 3000cps! The input level on the AP-50 was set below clipping for this test. 10K input resistance, 100 ohm output resistance, 12.6V power as specified for the AP-50

All the discussion points came together. If I were to put together another repeater, from the discussions, I would, go into the receiver to flat audio output that is de-emphasized, notch the RX PL tone, place the P-50 probably after the controller where the audio is still not pre-emphasized? so any desired clipping is done on flat audio? and depending on how the transmitter is configured, either do mic input or digital input, and probably no equilization required. The transmitter modulation limiter would either be bypassed via the digital input, or if the mic input was used, the mod limiter would need to set to at least 9 KHz peak for the repeater to pass up to 3KHz audio unimpeded. Actually I find about 2700cps is just fine for the repeat audio to sound same as direct especially if channel spacing is any tighter than 20 KHz.

John W1GPO

On 10/27/2022 9:35 AM Kevin Custer <kuggie@...> wrote:

John mentions the process on how he'd implement one audio processing product that is "out there".? I purposely didn't reference the AP-50 in my earlier post so people wouldn't consider the post a sales opportunity.

John says that he'd apply clipping to audio that's spectrally flat.? I wouldn't - and here's why.

Everyone knows the energy in the upper part of the frequencies for voice communications are considerably lower than the lower ones.? Clipping voice audio that's spectrally flat then doesn't apply as much processing to these upper frequencies that are lower in level.? I prefer to pre-emphasize the audio prior to clipping as it sounds better to me.? If you look at some of the exciters that have been used to build repeaters over the years, many of them, including the Motorola MICOR also pre-emphasize the audio before its application to the clipping stage.? In fact - some phase modulated exciters will pre-emphasize - clip - filter - de-emphasize and then feed the PM which ultimately pre-emphasizes the resulting audio.? Evidentially Motorola thought this sounded better too, otherwise they would not have gone through all of the pre - de machinations.? Motorola's FM exciters in this line simply deleted the de-emphasis stage so the resulting pre-emphasized - clipped - filtered audio was applied to the FM modulator.

The AP-50 is designed to allow the builder to choose which method they feel is best for them.? This is very casually mentioned in the AP-50's data sheet.

Like Bob Dengler said - the challenge is the overall headroom required.? Thankfully - with 12V applied to the output op-amp stage the circuit (just) makes it without adding clipping past the LPF, which would be terrible and defeat the protection the processing is supposed to provide in the first place.

Kevin W3KKC


On 10/26/2022 9:45 PM, John wrote:

This ongoing discussion on setting repeater audio stimulated me to check out Kevin's AP-50 which had been sitting in the workshop for years without being put to use. There has been absolutely no collusion or discussion with Kevin . Years ago I had made the enclosed graph on first a SyntorX9000 mic input audio vs deviation from 50-5000cps, and then as comparison a phase modulated Micor and then a FM?? modulated Micor, all on 6 meters. It is not quite apples vs apples because the modulation limiter was set for max dev at 1000cps of a bit more than +-6Kz on the X9000, unknown level on the phase modulated Micor, and +-9KHz? at 1000cps on the FM Micor. As you can see, the X9000 had an exactly even 6dB/ octave pre-emphasis from 50 to 2250 cps and a superior roll off above 3KHz. (could make a good sounding repeater). The AP-50 did not have the pre-emphasis option? hooked up before the clipper so you can see how flat it is between 250 and 3000cps, but wow what a comparatively steep roll off above 3000cps! The input level on the AP-50 was set below clipping for this test. 10K input resistance, 100 ohm output resistance, 12.6V power as specified for the AP-50

All the discussion points came together. If I were to put together another repeater, from the discussions, I would, go into the receiver to flat audio output that is de-emphasized, notch the RX PL tone, place the P-50 probably after the controller where the audio is still not pre-emphasized? so any desired clipping is done on flat audio? and depending on how the transmitter is configured, either do mic input or digital input, and probably no equilization required. The transmitter modulation limiter would either be bypassed via the digital input, or if the mic input was used, the mod limiter would need to set to at least 9 KHz peak for the repeater to pass up to 3KHz audio unimpeded. Actually I find about 2700cps is just fine for the repeat audio to sound same as direct especially if channel spacing is any tighter than 20 KHz.

John W1GPO

RLC controllers from Audio Test Solutions are alive and well, full stock, shipping in days, and growing. Visit .

Allan Overcast KF7FW

Audio Test Solutions,? Inc.

This ongoing discussion on setting repeater audio stimulated me to check out Kevin's AP-50 which had been sitting in the workshop for years without being put to use. There has been absolutely no collusion or discussion with Kevin . Years ago I had made the enclosed graph on first a SyntorX9000 mic input audio vs deviation from 50-5000cps, and then as comparison a phase modulated Micor and then a FM?? modulated Micor, all on 6 meters. It is not quite apples vs apples because the modulation limiter was set for max dev at 1000cps of a bit more than +-6Kz on the X9000, unknown level on the phase modulated Micor, and +-9KHz? at 1000cps on the FM Micor. As you can see, the X9000 had an exactly even 6dB/ octave pre-emphasis from 50 to 2250 cps and a superior roll off above 3KHz. (could make a good sounding repeater). The AP-50 did not have the pre-emphasis option? hooked up before the clipper so you can see how flat it is between 250 and 3000cps, but wow what a comparatively steep roll off above 3000cps! The input level on the AP-50 was set below clipping for this test. 10K input resistance, 100 ohm output resistance, 12.6V power as specified for the AP-50

All the discussion points came together. If I were to put together another repeater, from the discussions, I would, go into the receiver to flat audio output that is de-emphasized, notch the RX PL tone, place the P-50 probably after the controller where the audio is still not pre-emphasized? so any desired clipping is done on flat audio? and depending on how the transmitter is configured, either do mic input or digital input, and probably no equilization required. The transmitter modulation limiter would either be bypassed via the digital input, or if the mic input was used, the mod limiter would need to set to at least 9 KHz peak for the repeater to pass up to 3KHz audio unimpeded. Actually I find about 2700cps is just fine for the repeat audio to sound same as direct especially if channel spacing is any tighter than 20 KHz.

John W1GPO