Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Oh that's interesting, I've not seen the non DDS version of the 5680 yet. The frequency division for output in the non option 58 ones I've had hands on was definitely done in a CPLD chip, the DDS was "for internal use only" as far as I could tell. On 10 Jan 2017 09:07, "wb6bnq"

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hi Clint, Actually there are two versions of the 5680. The older version is exactly like the 5650 option 58 composition. The newer version has the DDS as part of the signal generation for the physics package. And it appears that they may be using an FPGA programmed as a divider to provide

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Yes, in the 5650 there's only DDS on opt 58, in the 5680 there is one in the main loop too, my bad for not being precise/muddled. On 10 Jan 2017 01:43, "wb6bnq" wrote: > HI Bob & Clint, > > If you look at the second message of this thread, I attached the manual > that applies

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

HI Bob & Clint, If you look at the second message of this thread, I attached the manual that applies to Option 58. Look at PDF page # 16 and you will see that there is no DDS in the physics package. The DDS is only used down stream in some variations of the product such as the Option 58

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Option 58 in a FE Rb is an additional sub board which has nothing to do with the physics package control loop. In an option 58 Rb there are two DDS chips. On 9 January 2017 at 17:48, Scott Stobbe wrote: > It very well could be. Based on Marks comments, it sounds

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

It very well could be. Based on Marks comments, it sounds like the DDS tone after being squared up is directly driving a 23-bit counter for the 1 PPS output. On Mon, Jan 9, 2017 at 12:17 PM, Bob kb8tq wrote: > Hi > > In most Rb’s (including the FE 56xx’s) the DDS is mixed with a

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hi In most Rb’s (including the FE 56xx’s) the DDS is mixed with a fixed microwave frequency signal. The DDS only has to make up “part” of the total offset. You get roughly a three orders of magnitude improvement because of this. Rick has gone into all the gory details of why it gets done this

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

A 32-bit DDS synthesizing at 1/5 Fs, yields a tuning resolution of ~ 1 ppb. So, I would imagine a slightly lower frequency is programmed into the DDS and the c-field is trimmed to yield a higher precision. If the new synthesized tone you wish to generate is an integer number of DDS codes you could

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hi Matt, Well, after rereading Mark’s paragraph in question, I think he did not properly develop his complete thoughts. The first statement about the Hydrogen Maser is absolute. The second statement is the one that is really vague. The third statement is the clue taken with the fact that

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

On 2017-01-04 10:16, wb6bnq wrote: Hello Bill Thanks for re-iterating over this. Yes, I do think the outer can covering is a MU-metal shield.  The bottom plate where the connector is located is not. That is reassuring thank you! I know the calculator that comes with Windows XP will

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

On 2017-01-04 11:08, Attila Kinali wrote: Hoi Attila So it's the usual curiosity and the need to have a reference for your 23cm radios? Yes exactly. Advantage of an GPSDO over an Rb is that you know it's on frequency, while with an Rb it can be off without you knowing it, if the

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hello Mathias, I did mis-speak. You're correct that only 32 bits (8 hex digits) are used to program the DDS chip. As Mark points out they store a 64 bit number and only use 56 bits but he does not elaborate on what is done with the bits beyond 32. Also, after reviewing my comment on the

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hoi Mathias! On Tue, 03 Jan 2017 17:55:32 +0100 Mathias Weyland wrote: > On 2017-01-02 12:18, Attila Kinali wrote: > > May I ask what you want to achieve? Resp. what you need a 10MHz > > reference for? > > I've always been wondering about those devices, I guess out of pure

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

On 2017-01-02 12:18, Attila Kinali wrote: Attila! Nice to see you around here ond au der es guez nois! May I ask what you want to achieve? Resp. what you need a 10MHz reference for? I've always been wondering about those devices, I guess out of pure curiosity. Once I learned that those

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

and if you glue a piece of non-magnetic material -- which could hold that connector -- it could be even some plastic, to the surface of the mu-metal , you do not need to worry about disturbing the magnetic conditions 73 KJ6UHN Alex On 1/2/2017 3:44 PM, Attila Kinali wrote: On Tue, 03 Jan

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

On Tue, 03 Jan 2017 11:02:54 +1300 Bruce Griffiths wrote: > Maybe a waterjet cutter would imapct less on the shielding properties of > tthe mumetal? I doubt it. mu-metal is pretty sensitive to vibration as well and a waterjet creates plenty of that. But anealing

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hi My biggest concern is that they magnetize the shield as they drill it. It’s a “static” field, but it’s a static *near* field. I doubt that is a good thing …. Bob > On Jan 2, 2017, at 5:53 PM, Bruce Griffiths > wrote: > > One could always wrap the assembly with

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

One could always wrap the assembly with its impaired mu metal shield in several layers of flexible magnetic shielding foil to regain the desired magnetic shielding e.Most such foils can be cut with scissors without significant effect on their magnetic properties. Bruce On Tuesday, 3

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hi > On Jan 2, 2017, at 5:02 PM, Bruce Griffiths > wrote: > > > Maybe a waterjet cutter would imapct less on the shielding properties of > tthe mumetal? > Maybe …. pretty good bet that the guys modifying these in their living room aren’t focused on much more

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Maybe a waterjet cutter would imapct less on the shielding properties of tthe mumetal? Bruce On Monday, January 02, 2017 12:58:55 PM Bob Camp wrote: > Hi > > > On Jan 1, 2017, at 7:31 PM, wb6bnq wrote: > > > > Hello Mathias, > > > > I think you did not quite understand how

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hi > On Jan 1, 2017, at 7:31 PM, wb6bnq wrote: > > Hello Mathias, > > I think you did not quite understand how the calibration process works with > that unit. The factory procedure is to set the pot to minimum and then bring > the DDS up to the step that produces the

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

On 2017-01-02 01:31, wb6bnq wrote: Hello Bill Thanks for your response and the pdf manual. There's lots of good information in there. You are certainly right in that there's a few things that I have not understood. Unfortunately this has not changed after having read your response: That "R"

Re: [time-nuts] FE-5650A option 58 tuning word for 10 MHz output

Hoi Mathias! Wie goht's wie stoht's? :-) On Sat, 31 Dec 2016 15:33:53 +0100 Mathias Weyland wrote: > I'm new to this list. I got myself a FE-5650A Rubidium Standard off of > ebay. > It's the "option 58" 1 pps output variant, hence I have to modify the > tuning > word used