<html><head></head><body style="zoom: 0%;"><div dir="auto">There may be multiple ways to get there and I have a lot of experiments to do before I'l know if this ideawill work with the uBlox modules. The complication is that none of the modules accept an external clock input so creativity will be required. Sometime in the next few days I'll put together an initial description of the options.</div>
<div class="gmail_quote" >On Sep 22, 2019, at 11:46 AM, Rick - W2GPS <<a href="mailto:w2gps@cnssys.com" target="_blank">w2gps@cnssys.com</a>> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre class="blue">John,<br><br>I think we can make this work without "magic" by picking the right OCXO, carefully adjusting the setup parameters in the M8F and possibly adding a processor in series with the D/A to do additional filtering. Nevertheless, your "magic" is interesting, too.<br><br>Rick<br>W2GPS<br><br><br>-----Original Message-----<br>From: John Ackermann N8UR <jra@febo.com> <br>Sent: September 21, 2019 5:36 PM<br>To: Rick - W2GPS <w2gps@cnssys.com>; 'TAPR TangerineSDR Modular Software Defined Radio' <tangerinesdr@lists.tapr.org><br>Subject: Re: [TangerineSDR] TangerineSDR Board Sizes and Mock-up<br><br>The "magic" I'm working on is whether we can use real time corrections via internet or another mechanism to reduce the GPS noise. It appears we may be able to reduce the ADEV by an order of magnitude. If we do that, the loop time constant can be shorter which would allow for a cheaper oscillator. But there's still a bunch of testing to do to confirm that and figure out a final design.<br><br>On 9/21/19 5:00 PM, Rick - W2GPS wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;"> John,<br> <br> I noticed the various layout examples in the SiLabs 53xx documentation <br> but I did not notice the 6-layer requirement. At present, the board <br> stack is 4-layer, 80mm (0.31") thick to match the M.2 specification. <br> It is set up to match the stack-up requirements for standard <br> configuration from low cost board houses like <a href="http://4pcb.com">4pcb.com</a>. I just checked <br> and it will be easy to change this to 6-layer, 80mm (0.31") thick <br> board while staying within their low cost board structure.<br> <br> I will need to find a low cost TCXO for the base configuration. The <br> OCXO I show is well over $100 in 50-piece quantity. It can get to <br> twice that if over specified. I hope the footprints can be overlaid to save room.<br> <br> The board size will be a challenge, I'm sure.<br> <br> Rick<br> W2GPS<br> <br> <br> -----Original Message-----<br> From: TangerineSDR <tangerinesdr-bounces@lists.tapr.org> On Behalf Of <br> John Ackermann N8UR via TangerineSDR<br> Sent: September 21, 2019 4:43 PM<br> To: tangerinesdr@lists.tapr.org<br> Cc: John Ackermann N8UR <jra@febo.com><br> Subject: Re: [TangerineSDR] TangerineSDR Board Sizes and Mock-up<br> <br> Thanks, Rick. I've finally started paying attention and have been <br> thinking about some unique GPSDO ideas. They may change the physical <br> parts a bit but we're a long way from having anything finalized.<br> <br> I think we've concluded that the RF output from the M8F module is not <br> acceptable for RF use -- it has a very ugly dither pattern so we will <br> likely need a external (TC)(OC)XO and DAC no matter what architecture <br> we end up with.<br> <br> One thing to note: the SiLabs 53xx chip wants a 6 layer board and also <br> has some fairly funky layout requirements; a bunch of this is due to <br> crosstalk reduction, and the 48 MHz crystal used as the cleanup <br> oscillator. The chip is physically small, but pretty complex to lay out.<br> <br> 73,<br> John<br> <br> On 9/21/19 4:24 PM, Rick - W2GPS via TangerineSDR wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;"> All,<br><br> I have been working on the clock module to see if the proposed size <br> for<br></blockquote> the clock module is reasonable. Attached is a 3D top view showing <br> major components. Not shown is the D/A to drive the OCXO and various <br> minor components. These may wind up on the bottom of the board.<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;"><br> Rick<br> W2GPS<br><br> -----Original Message-----<br> From: TangerineSDR <tangerinesdr-bounces@lists.tapr.org> On Behalf Of <br> Scotty Cowling via TangerineSDR<br> Sent: September 17, 2019 11:50 AM<br> To: TAPR TangerineSDR Modular Software Defined Radio <br> <tangerinesdr@lists.tapr.org><br> Cc: Scotty Cowling <scotty@tonks.com><br> Subject: [TangerineSDR] TangerineSDR Board Sizes and Mock-up<br><br> Here is a sneak preview of part of the TangerineSDR talk I will be <br> giving<br></blockquote> at DCC on Saturday.<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;"><br> Rick, this should be enough information on the PCB sizes to figure <br> out if<br></blockquote> we have enough room or not.<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;"><br> The CKM can be extended downward and/or to the right (when looking at <br> the<br></blockquote> assembly with the RPi I/O connector on top). We may have to make the <br> DE board larger anyway, if our CAD guy needs more routing room.<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #ad7fa8; padding-left: 1ex;"><br> 73,<br> Scotty WA2DFI</blockquote><br><br> <br> <br> --<br> TangerineSDR mailing list<br> TangerineSDR@lists.tapr.org<br> <a href="http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org">http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org</a><br> <br></blockquote><br><br></pre></blockquote></div></body></html>