Is there an advantage to installing the Flex GPSDO option, or is picking up an unit on eBay sufficie

Mike - K6QY

Post-purchase GPSDO acquisition options?

Mark Erbaugh

At one point several years ago, Flex mentioned the possibility of using the time from the internal GPS to time stamp the data (VITA) packets allowing diversity reception with remote flexes, but to my knowledge this has not been implemented, the GPS is used only as a frequency standard. There been requests to implement a NTP server in the flex, but I don’t think that has been done either. So other than having one less box on the shelf there is no advantage to the internal GPS.

Ted VE3TRQ

As I see it, other than cost (an eBay item would be cheaper), there is one other advantage to the eBay GPSDO - they (almost) all have a PPS and RS232 output, allowing you to either keep a PC updated with ntp or NMEATime, or actually create an ntp server (on one of your PCs) disciplined by that GPSDO. You then have the advantage of providing accurate time to all your other PCs on the network (including those at a Field Day or other sites with no Internet).

Bill W2PKY

Thomas NE7X

Steve K9ZW

My take is the VITA-49 packets use the radio-server’s (aka Flex-6x00) timestamp. The extra accuracy across several Flex-6000s to (hopefully) combine signals will depend on each 6000 being synced to a common time reference. This clock side of the GPSDO may be what sets it apart from an external frequency reference. Currently as of April 2019 I’m thinking there is no difference but down the road the timing would look to gain importance. 73 Steve K9ZW

Ted VE3TRQ

If the radio has an ntp client in it (any self-respecting Linux computer should), it won’t make any difference if you have an internet connection or a local ntp server :-) At least if the radio has some way of discovering the ntp server :-(

John - AI4FR

KF4HR

I bought the same GPSDO that Bill is using (eBay purchase).  It made a major difference in the Frequency Offset Number (under Radio Setup -> RX -> Offset (in ppb).  Without the GPSDO I was seeing numbers in the 900 to 1100 range.  With the GPSDO my Frequency Offset Number typically reads 6.  I seem to remember being told this parameter does not relate to either the transmit or receive frequency stability, but rather the stability of some internal clock function.  In any case, I noticed no difference in operation with or without the GPSDO, even on the digital modes.

Steve K9ZW

Should clarify my take - the precision VITA-49 timestamping would become important when more than one digital data stream is merged. This is when I’m thinking the internal GPSDO would come into play by providing a GPS time reference. Not certain if the usual net based time servers could provide enough resolution to allow several distinctly recorded digital data streams to be manipulated in the same way. For the proposes of a frequency reference internal vs external should be insignificant. For the purposes of running digital mode the usual net based time syncing works. But if you want to combine and analyze say four streams each recorded at a different antenna site and process them a fifth site, things looks to require better time-stamping carefully synced. 73 Steve K9ZW

Kevin

KY6LA_Howard

I agree with Kevin.. Bought the GPSDO because I always buy everything fully loaded so I do not have buyer's envy that I did not get everything.

Plus there was an allegation from Matt who talked me into it, that it would be used in the future to time stamp packets for true geographic diversity.  5 years later, and no real geographic diversity...

Since I do not do the Frequency Measuring Tests, its sort of been a waste of money.

Mike - K6QY

I’m new to the community, a returning ham after 50y! And a new Flex owner. I am simply bowled over by the warmth, openness, and generosity of this community. Thank you all for your detailed responses!

Steve K9ZW

Ah, if everything marketing guys came true in the timeframe they imply we’d have wide area diversity and 500 mile battery packs for our cars that charge in 45 minutes..... Or maybe both are just around the corner? Imagination! 73 Steve K9ZW

John - AF3K

EA4GLI

I bought my 6700 with the GPSDO. If I could go back in time I would not do it. Adds no value to my station beside "bragging rights" at a very large price tag. I use it to discipline 440mhz and 1.2ghz transverters, but I could have easily done that with the ebay one and keep accurate time across my PCs to boot. GPSDO, usb dongle, ver 1 maestro,... I have had a lot of disappointments with Flex gear. But that is just me. YMMV.

EA4GLI

Enjoy the feeling while it lasts.

Clay N9IO

Mike,

I ordered a n eBay gpsdo this past weekend From an american vendor. A bunch if the guys in our local club are planning to do the FMT next week, thought I would get in on the fun and compare notes.

I am curious from a comment in this thread if a connected Windows computer can pick up the time from the Flex. I'd appreciate it if someone would answer that for me.

KY6LA_Howard

No... GPSDO in the Flex definitely cannot send time stamps to a PC

Clay N9IO

Thanks Howard.

John - AI4FR

Plus it is slightly less than a half a second off from the actual time. In other words you can watch the PC or listen to a legacy receiver tick off the seconds from WWV and the Flex with or without a GPSDO will be about a half a second late.

Mark WS7M

N8FNR

John WA7UAR

Since the topic of VITA-49 has come up here I wanted to share a recent thread with a video and pdf that discusses a (coming?) version 2 of the VRT protocols: https://community.flexradio.com/flexradio/topics/vrt-and-vita-49-a-video-and-discussion-about-radio-transport-protocol-objectives-overview-and-applications

Clay N9IO

Scott Russell - N1SER

Clay, a club member did FMT and was one of the 5 at the top. His was from the SunSDR2 Pro and an Ebay GPSDO. How did you guys do? I have an Ebay unit as well but missed the event. I was looking forward to it so maybe in the Fall.

Scott N1SER

Clay N9IO

Scott, Was going to start the install the day I received the gpsdo in the mail. Had good intentions but since I hadn't considered wanting to install the gpsdo at all when I first purchased the radio I didn't realize the SMA connectors did not come installed only if you ordered the factory gpsdo. Hadn't given it a thought. I get it now and will start the process once I have a better plan and parts required to do a clean installation. I need to know a little more about the 6600's internal connections as I noted below. Don't know how the guys in my group did but I guess I I'll give the FMT a go next time around. November I think it is. Bummer...

Clay N9IO

Scott you had a post about 4 months back I wish I had seen before the fact would have saved myself a bunch of time. Anyway figured it out all is good from the 10Mhz RCA Jack in the back of the 6600.

Clay N9IO