From:	RON4DTV -(RON4DTV)	TO:	ALL

Date Posted:	2002-4-3 3:38:00
Message: Body:	For approx 6 months I have been using a channel plus model 5615 mts stereo modulator to send DSR922 4DTV video/audio through out my house on uhf channel 37. The input to the channel plus comes from 4dtv fixed a/v composite outputs. I can record/listen to mts stereo surround in any room. This works great, with great sound and picture quality on all analog movie channels (4dtv channels below 100)!!!!! When digicipher (channels above 100) are sent on uhf channel 37 the surround channel has a breathing or sound of rushing air sound on these digital movie channels?????? Channel + has been investigating this problem for 6 mos and plans on obtaining a 4dtv loaner to investigate at the channel plus site. I have tried many combinations of settings on the 4dtv recvr audio settings, none of these resolves the breathing problem on digital movie channels modulated via the channel + box. At the present time I record all digital/analog movies in the living room via aux vcr inputs direct from the 4dtv receiver thus, bypassing the channel + box. This works fine, no sound problems encountered. I record all analog on chan 37 uhf thru out the house. this works fine. the problem is; once a digital move is modulated on the channel plus box the sound failure will occur. Note: also tried using variable outputs from 4dtv to channel + box. Sound on digital movie channels still has the same problem with the sound. As you can see we enjoy watching manny movies using the DSR922 4DTV receiver. we receive over a hundred movie channels thus record and catalogue these movies. Any input you guys have would be greatly appreciated. Thanks again, Ron (RON4DTV)

Date Posted:

2002-4-3 3:38:00

Message:
Body:

For approx 6 months I have been using a channel plus model 5615 mts stereo modulator to send DSR922 4DTV video/audio through out my house on uhf channel 37. The input to the channel plus comes from 4dtv fixed a/v composite outputs. I can record/listen to mts stereo surround in any room. This works great, with great sound and picture quality on all analog movie channels (4dtv channels below 100)!!!!! When digicipher (channels above 100) are sent on uhf channel 37 the surround channel has a breathing or sound of rushing air sound on these digital movie channels?????? Channel + has been investigating this problem for 6 mos and plans on obtaining a 4dtv loaner to investigate at the channel plus site. I have tried many combinations of settings on the 4dtv recvr audio settings, none of these resolves the breathing problem on digital movie channels modulated via the channel + box. At the present time I record all digital/analog movies in the living room via aux vcr inputs direct from the 4dtv receiver thus, bypassing the channel + box. This works fine, no sound problems encountered. I record all analog on chan 37 uhf thru out the house. this works fine. the problem is; once a digital move is modulated on the channel plus box the sound failure will occur. Note: also tried using variable outputs from 4dtv to channel + box. Sound on digital movie channels still has the same problem with the sound. As you can see we enjoy watching manny movies using the DSR922 4DTV receiver. we receive over a hundred movie channels thus record and catalogue these movies. Any input you guys have would be greatly appreciated.

Thanks again,
Ron (RON4DTV)

From:	STH - GI -(STHILL01)	TO:	RON4DTV

Date Posted:	2002-4-3 7:00:00
Message: Body:	I have an explanation for your problem, and also a suggestion for a solution. On DCII channels the audio D/A produces some low level, high frequency noise. This noise is too high in frequency to be audible (about 100kHz to 200kHz). And it is too low in level to affect most home audio equipment. But when you feed the audio into a cable modulator, things aren't so simple. Cable modulators pre-emphasize the audio before modulation. This means high frequency audio content gets accentuated. The high frequency noise was low level from the 922, but after going through the pre-emphasis circuit in your modulator, it is now much stronger. Then, after the audio goes through the modulator, the high frequency noise gets "folded" into the audible range, and so you can hear it. The best modulators include in the pre-emphasis filter an additional lowpass filter stage to prevent this from happening. But many modulators don't include this lowpass filter. So what you need is some sort of audio lowpass filter between the 922 and your modulator.

Date Posted:

2002-4-3 7:00:00

Message:
Body:

I have an explanation for your problem, and also a suggestion for a solution.

On DCII channels the audio D/A produces some low level, high frequency noise. This noise is too high in frequency to be audible (about 100kHz to 200kHz). And it is too low in level to affect most home audio equipment.

But when you feed the audio into a cable modulator, things aren't so simple. Cable modulators pre-emphasize the audio before modulation. This means high frequency audio content gets accentuated. The high frequency noise was low level from the 922, but after going through the pre-emphasis circuit in your modulator, it is now much stronger. Then, after the audio goes through the modulator, the high frequency noise gets "folded" into the audible range, and so you can hear it.

The best modulators include in the pre-emphasis filter an additional lowpass filter stage to prevent this from happening. But many modulators don't include this lowpass filter.

So what you need is some sort of audio lowpass filter between the 922 and your modulator.

From:	RON4DTV -(RON4DTV)	TO:	STH - GI

Date Posted:	2002-4-3 1:57:00
Message: Body:	STH-GI, Thanks for your help concerning ChannelPlus modulation of 4DTV digital sound. Tonight I purchased a Radioshack (GROUND-LOOP ISOLATOR, PART # 270-054) and installed it between the Dsr922 and the Channelplus mts stereo modulator. As of tonight I can now record all 4DTV digital and analog channels successfully via channelplus mts stereo modulated on uhf channel 37 (With no distortation of digital sound)in any part of the house. Thanks again for your help, it was greatly appreciated. I am a newcommer to the forum and find the 4DTV forum very helpful and interesting. I hope a time comes when I can return the favor. I really enjoy my DSR922 receiver and the availability of so many analog/digital movies and digital music channels. Hope the future looks bright for C-BAN. Thanks again, RON4DTV

Date Posted:

2002-4-3 1:57:00

Message:
Body:

STH-GI, Thanks for your help concerning ChannelPlus modulation of 4DTV digital sound. Tonight I purchased a Radioshack (GROUND-LOOP ISOLATOR, PART # 270-054) and installed it between the Dsr922 and the Channelplus mts stereo modulator. As of tonight I can now record all 4DTV digital and analog channels successfully via channelplus mts stereo modulated on uhf channel 37 (With no distortation of digital sound)in any part of the house. Thanks again for your help, it was greatly appreciated. I am a newcommer to the forum and find the 4DTV forum very helpful and interesting. I hope a time comes when I can return the favor. I really enjoy my DSR922 receiver and the availability of so many analog/digital movies and digital music channels. Hope the future looks bright for C-BAN.

Thanks again,
RON4DTV

From:	TSGORDON -(TSGORDON)	TO:	RON4DTV

Date Posted:	2002-4-3 5:04:00
Message: Body:	I found the explaination about pre-emphasis to be astounding. Evidently, someone knows how to build these things. I would have speculated that this was more of a low bit-rate meets high bandwidth sampeling problem. Anyway, I bought a Cable Labs 2000, thinking I had ordered a Channel Plus, for use with the 920. We tried it with a Toshiba DVD player first and it blew-out after 3 minutes. The "DVD audio bandwith is too great for all but our 2000 Gold series" -their tech explained. Someone else said it was just a Toshiba thing. I think the ascribed solution was to try a different company, or forgo 'modulation'. That's when I started building all 'composite'-based household solutions using the Xantech 1X6 Distribution amps. I also do A/B/C RF's to every room in a new house, assuming there's a $$ budget. The tiny new ChannelPlus 4 Channel digital modulators are the best way to go with multiple satellite receivers. It's enough to make you watch DBS every now and then...

Date Posted:

2002-4-3 5:04:00

Message:
Body:

I found the explaination about pre-emphasis to be astounding. Evidently, someone knows how to build these things. I would have speculated that this was more of a low bit-rate meets high bandwidth sampeling problem.

Anyway, I bought a Cable Labs 2000, thinking I had ordered a Channel Plus, for use with the 920. We tried it with a Toshiba DVD player first and it blew-out after 3 minutes. The "DVD audio bandwith is too great for all but our 2000 Gold series" -their tech explained. Someone else said it was just a Toshiba thing. I think the ascribed solution was to try a different company, or forgo 'modulation'. That's when I started building all 'composite'-based household solutions using the Xantech 1X6 Distribution amps. I also do A/B/C RF's to every room in a new house, assuming there's a $$ budget.

The tiny new ChannelPlus 4 Channel digital modulators are the best way to go with multiple satellite receivers. It's enough to make you watch DBS every now and then...

From:	RON4DTV -(RON4DTV)	TO:	TSGORDON

Date Posted:	2002-4-3 6:00:00
Message: Body:	Tsgordon, Good luck with using a Channel Plus modulator. The model 5615 MTS Stereo/Surround modulator works fine, after I installed a Radioshack 'GROUND LOOP ISOLATOR(part # 270-0054 $15.95)' BETWEEN THE DSR922 AND THE CHANNEL PLUS MODULATOR'. This resolved the background noice problem. Now getting good quality recorded or listening pro-logic surround / stereo music through out the house via UHF channel 37. Good luck with your Everything. RON4DTV

Date Posted:

2002-4-3 6:00:00

Message:
Body:

Tsgordon, Good luck with using a Channel Plus modulator. The model 5615 MTS Stereo/Surround modulator works fine, after I installed a Radioshack 'GROUND LOOP ISOLATOR(part # 270-0054 $15.95)' BETWEEN THE DSR922 AND THE CHANNEL PLUS MODULATOR'. This resolved the background noice problem. Now getting good quality recorded or listening pro-logic surround / stereo music through out the house via UHF channel 37. Good luck with your Everything.

RON4DTV