Re: [ntp:questions] Help getting IRIG working
The clock puts out all of its signals on BNC. I'm not clear on the nomral assumptions with such wiring; for example, does one normally connect everything with BNC-T's, with the first and last T terminated with a 50ohm resister, or should I just connect direct through? It's audio you don't need any terminations to avoid reflections. (Well maybe if you have a few spools of coax in your setup.) This is where its perhaps most problematic for me...how do I know what's wrong with the input? How do I know what the input is supposed to do? It seems, for example, level adjustment is just guess-and-test with no way to know if I'm making it better or worse..how should one normally do this? The driver adjusts the gain. That value shows up in clockstats. Find it and watch it as you experiment. It should go to 255 when you disconnect the signal. As Dave Mills said, you will probably need an external attenuator to reduce the volume to a reasonable range. I used clip leads and resistors until I found something that worked. -- These are my opinions, not necessarily my employer's. I hate spam. ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Help getting IRIG working
On Fri, Apr 1, 2011 at 10:57 AM, Jim Kusznir jkusz...@gmail.com wrote: Hello all: I'm trying to set up a linux ntp server using IRIG as a time source, from a SEL 2407 (http://www.selinc.com/sel-2407/). Unfortunately, I've not managed to get this running yet. I think the best way to verify the gain and levels are set correctly could be one of the software oscilloscope programs that will plot the input from line in to the screen. Verify the signal is using most of the range and that it s not being clipped. There are a few free software 'scopes. The scope would also allow you to verify that valid time code is in fact there. Also I wonder if the line in jack is mono or stereo on your computer and if stereo the cable supplies signal to both channels. -- = Chris Albertson Redondo Beach, California ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Help getting IRIG working
On Fri, Apr 1, 2011 at 10:57 AM, Jim Kusznir jkusz...@gmail.com wrote: Hello all: I'm trying to set up a linux ntp server using IRIG as a time source, from a SEL 2407 (http://www.selinc.com/sel-2407/). Unfortunately, I've not managed to get this running yet. Have you tried flag3 to enable audio monitoring? This should allow you to hear the IRIG signal on the computer's speakers. Hearing the signal would 100% verify that the signal is being input. -- = Chris Albertson Redondo Beach, California ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
Re: [ntp:questions] Help getting IRIG working
Chris Co., The usual problem is overdriving the computer input.. Most IRIG devices produce a modulated signal in the range 10 V P-P, which is far larger than the line-in level. You might need an attenuator to produce in the order of 1 V P-P. As Chris says, the best way is to monitor the line out signal using the computer speaker. With a little practice, it is possible to slowly increase the input level until the speaker changes tone or becomes raspy. The bottom line is to monitor the AGC signal with that trace and bracket the input signal so the AGC reads in the middle of the range about 127. Dave Dave Chris Albertson wrote: On Fri, Apr 1, 2011 at 10:57 AM, Jim Kusznir jkusz...@gmail.com wrote: Hello all: I'm trying to set up a linux ntp server using IRIG as a time source, from a SEL 2407 (http://www.selinc.com/sel-2407/). Unfortunately, I've not managed to get this running yet. Have you tried flag3 to enable audio monitoring? This should allow you to hear the IRIG signal on the computer's speakers. Hearing the signal would 100% verify that the signal is being inpu ___ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
