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DDS Success

We redesigned the DDS (Direct Digital Synthesizer) for prototype II because it wasn’t meeting design goals for phase noise after being up-converted to our 740MHz LO.

LO = (Fout-IF)*2

Noise present in the LO appears in the final output and limits the amount of amplification available. This is why many HTs and other integrated radio products cannot be attached to power amps and stay legally in the channel.

The new design is working now and tests show adequate margin to take this design to production. This is a significant milestone behind us and puts us one large step forward to production.

Bryan K7UDR

To learn more about PhaseNoise

Q1 Progress Report

Prototype 2 has come back from assembly and passed initial bring-up. It is now in RF characterization. I expect this prototype to be fully functional but require some changes for full power operation.

We will have a full report at the MicroHAMS Digital Conference.

Thanks for your patience,
Bryan, K7UDR

Band Limited SDR …

… and a lot of other stuff

From my 2013 DCC Presentation.

Thanks to Gary Pearce of for his videography.

Rag Chew in Portland OR

I’ll be speaking with the hams of TERAC on Thursday evening for anyone in the Portland OR area that is interested in the latest developments on the UDRX.

Pre-Meeting Dinner at 6pm
Meeting starts at 7:30

Max’s Fanno Creek Brew Pub
12562 SW Main St
Tigard OR 97223

UDR Available for Pre-Order Confirmation

Season’s Greetings to all of you!

Dennis has the TX and RX Paths operational and sensitivity looks good. The power path has also passed preliminary bring-up. I am finalizing the layout over the Holidays and will be in Fab in a week or so.

For those of you who pre-ordered, You may increase or decrease your quantity up to a maximum of 5 units. Your call-sign is your discount code.

Please confirm by December 31st 2013.


Delivery will be in Q2 and you will not be charged until we have final specifications and a confirmed manufacturing slot.

We will  accept new orders at that time as well as accessories.

Thanks for making the UDR a reality!
Bryan, Basil, John and Dennis

UDR Progress Report

Hello All,

Basil delivered  the IQ ADC/DAC driver earlier this month and Dennis has an initial port of the modem completed, so we are moving into RF characterization. Once the transmit chain has been checked out, I will be working on the PA, RX/TX switch and thermal characterization while Dennis proceeds with the receive chain.

I have started layout on prototype II. I anticipate a third spin on the prototype before moving to pilot production in China.

We will not accept orders until I have fully functional prototypes in hand and then there is a 8-12 week production cycle.

Best case is orders this year for delivery in late Q1.

The initial deliverable includes:

  • 9600 MSK and 4800 GMSK Modems
  • Support for AX.25 and D-STAR DV
  • Winlink Client/Server
  • APRS Tracker/IGate
  • D-STAR IrcDDB Gateway
  • Hi-Speed Test Mode*

D-STAR Voice using the AMBE add-on card will be released after initial shipments are complete.

*We are not implementing legacy 56k support as there is little installed equipment and our engineering efforts are better spent on faster modes with FEC. The Hi-Speed Test will allow us to prove out our hardware and start gathering channel characterization data.

Full support for Hi-Speed TCP/IP and D-STAR DD will be a free Software Update in Q3 2014.

Thanks to all of you for your patience and support,
Bryan Hoyer, K7UDR

Breaking the 100kbit Barrier

At DCC this year we announced our intention to develop a new open-source Link Protocol and Modem specifically for high speed Amateur Radio Networking.

Preliminary Specifications, 100kHz Channel, 70cm band:

  • 4FSK or QPSK Modulation (2bits/symbol) up to 170kbps*
  • Forward Error Correction (FEC)
  • Automatic Repeat reQuest (ARQ)
  • IPv6 Friendly
  • Support for TCP, UDP and RTP
  • Authentication
  • Designed to work with Ad-Hoc Networking

In addition we will scale this down to 42.5kbps in a 25kHz Channel.

This will be a modular design to allow for experimentation with different modems and FEC and have built-in negotiation so nodes with different capabilities can achieve optimal communications.

This is a clean sheet design after reviewing all of the available open standards. Remember, this is a hi-speed data mode not a narrow band voice mode like D-STAR DV, DMR, P25 etc. We expect a lot of user feedback, testing and changes next year before this becomes any kind of Amateur Radio Standard.

We are in discussions with TAPR to act as the keeper of the spec as they do for AX.25 and will have a formal announcement at Pacificon next month.

Your feedback is requested, please post your questions and comments on the Yahoo Groups forum.

*see separate post: ARRL Moves to Kill Speed Limit

ARRL Moves to Kill Speed Limit

The ARRL stated in the September QST that it will file a Petition for Rule Making to delete all references to symbol rate. Although the article was focused on HF, an email exchange with the ARRL confirmed:

“The Board’s instruction is to seek the deletion of all references to symbol rate in 97.307(f). That includes (f)(5) and (f)(6). There is already a bandwidth limit in those subparagraphs.”

This will allow us to move past 56k until we  fully occupy the channel.

For the 70 cm Band §97.307(f)(6) applies

A RTTY, data or multiplexed emission using a specified digital code listed in §97.309(a) of this part may be transmitted. The symbol rate must not exceed 56 kilobauds. A RTTY, data or multiplexed emission using an unspecified digital code under the limitations listed in §97.309(b) of this part also may be transmitted. The authorized bandwidth is 100 kHz.


Upcoming Events

We’ll be at the Summer Gathering in North Bend WA this weekend (Sep 6-8) talking about changes to the FCC Regs and how that affects the UDR56k.

Then catch us at DCC in Seattle, after which we’ll release our progress update.

It’s Q3, Where’s my UDR?

Yes it’s officially Q3 but we still have a ways to go.

Rather than posting new guesstimates of when we’re going to ship, we’ll keep you informed of our progress.

Major Milestones:

  • Beta Unit HW/SW Integration
  • D-STAR Integration
  • Power Amp/Thermal Characterization
  • Extrusion release to manufacturing
  • Web interface  0.5 Published on the Web
  • Pilot Build PCB CPU and Radio
  • Order Confirmation/Release to Manufacturing
  • Initial limited production assembly and test
  • Production rollout

Bryan K7UDR