[TangerineSDR] TangerineSDR Board Sizes and Mock-up

Sun Sep 22 12:16:39 EDT 2019

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.

On Sep 22, 2019, 11:46 AM, at 11:46 AM, Rick - W2GPS <w2gps at cnssys.com> wrote:
>John,
>
>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.
>
>Rick
>W2GPS
>
>
>-----Original Message-----
>From: John Ackermann N8UR <jra at febo.com> 
>Sent: September 21, 2019 5:36 PM
>To: Rick - W2GPS <w2gps at cnssys.com>; 'TAPR TangerineSDR Modular
>Software Defined Radio' <tangerinesdr at lists.tapr.org>
>Subject: Re: [TangerineSDR] TangerineSDR Board Sizes and Mock-up
>
>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.
>
>On 9/21/19 5:00 PM, Rick - W2GPS wrote:
>> John,
>> 
>> I noticed the various layout examples in the SiLabs 53xx
>documentation 
>> but I did not notice the 6-layer requirement. At present, the board 
>> stack is 4-layer, 80mm (0.31") thick to match the M.2 specification. 
>
>> It is set up to match the stack-up requirements for standard 
>> configuration from low cost board houses like 4pcb.com. I just
>checked 
>> and it will be easy to change this to 6-layer, 80mm (0.31") thick 
>> board while staying within their low cost board structure.
>> 
>> I will need to find a low cost TCXO for the base configuration. The 
>> OCXO I show is well over $100 in 50-piece quantity. It can get to 
>> twice that if over specified.  I hope the footprints can be overlaid
>to save room.
>> 
>> The board size will be a challenge, I'm sure.
>> 
>> Rick
>> W2GPS
>> 
>> 
>> -----Original Message-----
>> From: TangerineSDR <tangerinesdr-bounces at lists.tapr.org> On Behalf Of
>
>> John Ackermann N8UR via TangerineSDR
>> Sent: September 21, 2019 4:43 PM
>> To: tangerinesdr at lists.tapr.org
>> Cc: John Ackermann N8UR <jra at febo.com>
>> Subject: Re: [TangerineSDR] TangerineSDR Board Sizes and Mock-up
>> 
>> Thanks, Rick.  I've finally started paying attention and have been 
>> thinking about some unique GPSDO ideas.  They may change the physical
>
>> parts a bit but we're a long way from having anything finalized.
>> 
>> I think we've concluded that the RF output from the M8F module is not
>
>> acceptable for RF use -- it has a very ugly dither pattern so we will
>
>> likely need a external (TC)(OC)XO and DAC no matter what architecture
>
>> we end up with.
>> 
>> One thing to note: the SiLabs 53xx chip wants a 6 layer board and
>also 
>> has some fairly funky layout requirements; a bunch of this is due to 
>> crosstalk reduction, and the 48 MHz crystal used as the cleanup 
>> oscillator.  The chip is physically small, but pretty complex to lay
>out.
>> 
>> 73,
>> John
>> 
>> On 9/21/19 4:24 PM, Rick - W2GPS via TangerineSDR wrote:
>>> All,
>>>
>>> I have been working on the clock module to see if the proposed size 
>>> for
>> the clock module is reasonable. Attached is a 3D top view showing 
>> major components. Not shown is the D/A to drive the OCXO and various 
>> minor components. These may wind up on the bottom of the board.
>>>
>>> Rick
>>> W2GPS
>>>
>>> -----Original Message-----
>>> From: TangerineSDR <tangerinesdr-bounces at lists.tapr.org> On Behalf
>Of 
>>> Scotty Cowling via TangerineSDR
>>> Sent: September 17, 2019 11:50 AM
>>> To: TAPR TangerineSDR Modular Software Defined Radio 
>>> <tangerinesdr at lists.tapr.org>
>>> Cc: Scotty Cowling <scotty at tonks.com>
>>> Subject: [TangerineSDR] TangerineSDR Board Sizes and Mock-up
>>>
>>> Here is a sneak preview of part of the TangerineSDR talk I will be 
>>> giving
>> at DCC on Saturday.
>>>
>>> Rick, this should be enough information on the PCB sizes to figure 
>>> out if
>> we have enough room or not.
>>>
>>> The CKM can be extended downward and/or to the right (when looking
>at 
>>> the
>> assembly with the RPi I/O connector on top). We may have to make the 
>> DE board larger anyway, if our CAD guy needs more routing room.
>>>
>>> 73,
>>> Scotty WA2DFI
>>>
>>>
>> 
>> 
>> --
>> TangerineSDR mailing list
>> TangerineSDR at lists.tapr.org
>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>> 
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