26-12-2017, 11:52 PM
Hi Jeffrey
I don't believe the TVP5150 can be forced to PAL. The TVP5146 that I was using I am fairly sure could.
I have decided to use a switch to select the test pattern as opposed to have it atomatic on no signal, I thought it is easier to flick a switch than to have to unplug when the test card was required.
I still find it hard to believe how fast, powerful, versatile and flexible FPGA's can be, what a truly dream device if there was ever one. They may be a little harder than PIC's to program but the pay back is HUGE and that is putting it very mildly.
The photo below shows the scope trace (50mV/2mS Div.) on pin 14 (RF PLL loop filter) of the MC44BS373 modulator for sound when channel 13 is selected, it should be a flat line and is a flat line on all other channels. On the vision modulator it remains flat for all channels including 13. I swapped all the configuration settings between the vision and sound modulators and the problem switched to the vision modulator, so not a hardware problem. I don't think it is a configuration problem either as apart from frequency the configuration is the same for all channels. I will have another look at it tomorrow. I built a MC44BS373 based modulator a couple of years ago and it had the same problem with channel 13, I never looked into it as channel 13 is not one I have much use for. It might just be a spooky 13 thing
I haven't used a 3.5 MHz trap before the modulator as I don't think there is need for it. I tried the converter on a modulator with a trap and detuning the trap made no noticeable difference on sound
Frank
I don't believe the TVP5150 can be forced to PAL. The TVP5146 that I was using I am fairly sure could.
I have decided to use a switch to select the test pattern as opposed to have it atomatic on no signal, I thought it is easier to flick a switch than to have to unplug when the test card was required.
I still find it hard to believe how fast, powerful, versatile and flexible FPGA's can be, what a truly dream device if there was ever one. They may be a little harder than PIC's to program but the pay back is HUGE and that is putting it very mildly.
The photo below shows the scope trace (50mV/2mS Div.) on pin 14 (RF PLL loop filter) of the MC44BS373 modulator for sound when channel 13 is selected, it should be a flat line and is a flat line on all other channels. On the vision modulator it remains flat for all channels including 13. I swapped all the configuration settings between the vision and sound modulators and the problem switched to the vision modulator, so not a hardware problem. I don't think it is a configuration problem either as apart from frequency the configuration is the same for all channels. I will have another look at it tomorrow. I built a MC44BS373 based modulator a couple of years ago and it had the same problem with channel 13, I never looked into it as channel 13 is not one I have much use for. It might just be a spooky 13 thing
I haven't used a 3.5 MHz trap before the modulator as I don't think there is need for it. I tried the converter on a modulator with a trap and detuning the trap made no noticeable difference on sound
Frank
