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as he says a low pass filter will produce a quasi sine wave "gaussian responce"
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From: lothar baier To: hp_agilent_equipment@... Sent: Tuesday, November 20, 2007 5:58 PM Subject: RE: [hp_agilent_equipment] 8640B External Reference sorry i wasnt to clear on that, the DDS i was refering to actually has a clock multiplier build in that allow a max of 30MHz i think. Mike Feher <n4fs@...> wrote: If you use 10 MHz as a clock for a DDS, then, you are just as well off using a flip-flop. Your output will be just a 5 MHz square wave either way. Now if you were to multiply the 10 MHz up first, like even just doubling it to 20 MHz, then you will have easily exceeded Nyquist and you also have room to put in a nice filter for 5 MHz. Still, the best recommendation was the first one. Just divide by two and filter. You may not even need to filter as most counters use a square wave anyway. 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 _____ From: hp_agilent_equipment@... [mailto:hp_agilent_equipment@...] On Behalf Of lothar baier Sent: Tuesday, November 20, 2007 5:37 PM To: hp_agilent_equipment@... Subject: Re: [hp_agilent_equipment] 8640B External Reference 5MHz was quite common back then, it had to do with the fact that 5MHz XO had a better phasenoise, you will also find 5MHz on many older rubidium and cesium beam standarts. You have basically two options, the first one is to just use a 2/1 frequency divider, you can find those at any semiconductor company fairly cheap, the other solution which is a bit more intricat is to use a DDS chip to generate your 5MHz out of a 10MHz XO "Richard W. Solomon" <w1ksz@earthlink. <mailto:w1ksz%40earthlink.net> net> wrote: After moving to Arizona I know have at least one of my GPS Stabilized Oscillators up and running. I intend to use the 10 MHz output as the External Reference for a couple of EIP Counters and I had hoped my 8640B. But, HP in their infinite wisdom, has deemed that a 5 MHz reference is needed. Is there any way to change that from 5 MHz to 10 MHz ? Maybe I should just stick 10 MHz in and see what happens ?? Any thoughts on this ? Thanks, Dick, W1KSZ/7 --------------------------------- Never miss a thing. Make Yahoo your homepage. --------------------------------- Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See how. |
