I thought I'd share some recent results for 2 useful frequency dividers.
For frequencies above 50MHz, an A-D 9513; and a 74HC4059 for
40 MHz below. The A-D 9513 likes higher slew rates works
best above 100MHz. I cheated and bought an evaluation board for
the A-D 9513; layout is really
Pete
You can probably do much better with the AD9513 at lower frequencies if
you use a couple of cascaded longtailed pairs each with carefully
selected gain (series feedback R between the longtailed pair emitters)
and bandwidth (capacitor between the collectors) to condition the low
frequency
Hi All;
All this frequency divider conjecture makes me think someone ought to come up
with a modern design regenerative divider!
Perhaps a double balanced mixer and a couple of high speed OP amps!
Regards; Rich
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time-nuts mailing list --
Rich and Marcia Putz wrote:
Hi All;
All this frequency divider conjecture makes me think someone ought to come up
with a modern design regenerative divider!
Perhaps a double balanced mixer and a couple of high speed OP amps!
Regards; Rich
___
Randy
In August you asked
First off, what I am about to do is ask a REALLY STUPID question, but
more and more of the GPS stuff I do is drifting towards the precision
timing end of things, so I thought I should ask.
I have been seeing a lot of traffic concerning making 10MHz frequency
In a message dated 8/8/2006 17:21:56 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Said,
I understand that the micros work fine, it just seemed like you would
need a second one to discipline the OCXO because of the timing
constraints on the divider.
Hi Randy,
on our new GPSDO's
At 5:31 PM -0400 8/8/06, John Ackermann N8UR wrote:
Randy Warner said the following on 08/08/2006 03:23 PM:
I have been seeing a lot of traffic concerning making 10MHz frequency
dividers using PIC's. While they provide an elegant solution to
providing an accurate 1PPS from a precision
Hi Said,
Thanks for the info, I did check the Philips (and Sparkfun) web site(s)
and I must admit the ARM chip is cheap and has impressive
specifications. With the GNU tools, I know it will work and it will fit
my homebrewer's budget :-) I used to consider $99 for a development kit
cheap, but
Guys,
First off, what I am about to do is ask a REALLY STUPID question, but
more and more of the GPS stuff I do is drifting towards the precision
timing end of things, so I thought I should ask.
I have been seeing a lot of traffic concerning making 10MHz frequency
dividers using PIC's. While
Hi Randy,
I guess they like the intellectual challenge of tweaking PIC bits :)
There is what I think may be a better way to generate the 1PPS: you can use
an Arm micro such as the Philips LPC2102 series to generate a 1PPS output
with 16.7ns settability:
these micros have counter/timers
Let me add this photo - I found in a box my first attempt
to make a PPS divider as well as an early breadboard
prototype of the much simpler, PIC-based, divider.
http://www.leapsecond.com/pages/ppsdiv/ver1.jpg
/tvb
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time-nuts mailing list
Randy Warner said the following on 08/08/2006 03:23 PM:
I have been seeing a lot of traffic concerning making 10MHz frequency
dividers using PIC's. While they provide an elegant solution to
providing an accurate 1PPS from a precision source, I have to ask if
there is a reason for going this
From: Tom Van Baak [EMAIL PROTECTED]
Subject: Re: [time-nuts] Frequency Dividers
Date: Tue, 8 Aug 2006 14:16:24 -0700
Message-ID: [EMAIL PROTECTED]
Let me add this photo - I found in a box my first attempt
to make a PPS divider as well as an early breadboard
prototype of the much simpler, PIC
:[EMAIL PROTECTED] On
Behalf Of John Ackermann N8UR
Sent: Tuesday, August 08, 2006 2:31 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Frequency Dividers
Randy Warner said the following on 08/08/2006 03:23 PM:
I have been seeing a lot of traffic concerning making
In a message dated 8/8/2006 14:29:38 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Hi Randy,
the Micro's allow you to do other stuff, like discipline the OCXO as well :)
BTW: I took a closer look at the Sparkfun board, the chip has a bunch more
Match outputs than I thought.
The
I understand that the micros work fine, it just seemed like you would
need a second one to discipline the OCXO because of the timing
constraints on the divider.
Correct. But at $2+/- each it's easy to use one uC
for a divider and another uC for the GPSDO algorithm.
Yet another for an IRIG
08, 2006 5:39 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Frequency Dividers
I understand that the micros work fine, it just seemed like you would
need a second one to discipline the OCXO because of the timing
constraints on the divider.
Correct
Tom Van Baak wrote:
I understand that the micros work fine, it just seemed like you would
need a second one to discipline the OCXO because of the timing
constraints on the divider.
Correct. But at $2+/- each it's easy to use one uC
for a divider and another uC for the GPSDO algorithm.
Yet
I have been seeing a lot of traffic concerning making 10MHz frequency
dividers using PIC's. While they provide an elegant solution to
providing an accurate 1PPS from a precision source, I have to ask if
there is a reason for going this route? I am just using three HCT40103
down counters
I have used a number of pll controlled microcontrollers, and I would not
recommend using one of those in a timing application such as those
discussed here.
These PLLs are generally not very clean spectrally (it's actually a good
thing for EMI, some chips have purposeful spread spectrum clocks)
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