Hi all, Status update - PCBs for the first batch are ready and we'll start populating soon. To date we're on time! :) See some PCB pictures here: http://openbts.chemeris.ru/2009/10/universal-clocking-unit-for-usrp-pcbs-are-ready/ Only when you hold it in hands, you realize how small and densely populated it is for all its features.
On Tue, Oct 20, 2009 at 01:31, Alexander Chemeris <[email protected]> wrote: > Hi all, > > As I wrote in my previous mail, we're working on an universal clock > source for USRP (and not only for USRP). It is based on 0.28ppm TCXO > from Connor Winfield [1], National Semiconductor LMX2531 VCO+PLL [2] > and LMK01000 CD [3] for clock generation and Atmel ATUSB for control. > So far we've finished PCB design and working on production of the first > 25 units. We'll reserve 5 of them for our own use and testing of > different options, 8 others are requested by community people, so there > are more then 10 left for sale. We plan to finish production at > the beginning of Dec and take units to 26C3. If you plan to attend it, > you have a great chance to see them, play with them and take some of > them with you. ;) > > As we promised, units form this experimental batch will be sold out > for only $100 or 66EUR (without shipping). We kindly invite everyone > interested in such unit to get one and try fitting it to your setup. > Also we need your help determining the best feature set for the unit > (read on for the ample list of possible features). We aim at creating > a really flexible and cheap clocking unit, which may used by a broad > GnuRadio community and will best fit its needs. Unit with open source > software and open hardware. > > Now, lets get to facts. Board dimensions are 86x44mm (3.4" x 1.7") - > it is designed to work inside of USRP box with RFX boards installed > with no external connections. > > Default distribution version includes: > 1) Clock board with default options > 2) U.FL to SMA cable to connect to USRP > 3) Power cable to connect to USRP's fan connector > > Default board options: > 1) Control from miniUSB or 16-pin connector on USRP daughter boards. > It will be possible to write a GNURadio block to control clocks right > from GNURadio flowgraph! > 2) Power from 2-pin connector for connecting to USRP fan power > connector and 2-pin pass-throw to connect fan to. That is board is > connected between USRP and fan. > 3) One U.FL clock output with ability to generate frequency in the main > range 2.84-65.83MHz, and additional ranges 65.91-71.82MHz, > 72.5-79MHz, and more ranges higher with <=0.44Hz step. Output > levels are CMOS. This means that you can tune your clock precisely > ti whatever frequency you want. > 4) Initial frequency calibration 1ppm, temperature stability 0.28ppm, > holdover stability over 24h 0.32ppm [1]. Clock jitter will be measured > when first units arrive to us, I'll post measurement results here. > > Pretty simple and flexible isn't it? But what makes this clock unit really > universal is a set of available options. You may solder them by yourself > or request ready-to-use units from us - I will make some notes on price > changes and options compatibility below, mail me for details if you're > interested in particular configuration. We want to be as flexible as > possible to fulfill community need in flexible clock source. > > So, basic additional options include: > 1) Power may be taken from 2-pin connector, 6V jack input or from USB. > All power options are mutually exclusive. > 2) COM-port with RS-232 levels for clock control. This will add about 3.5$ > to the price. > 3) Up to 5 more additional U.FL outputs (6 outputs altogether), which > share VCO frequency, but may be independently divided in clock > distributor. 5 additional connectors will add 8-9$ to the price. > 4*) Output levels may be (a) 4 LVPECL (or CMOS) outputs and 2 LVDS > outputs, (b) 6 LVPECL (or CMOS) outputs, (c) 6 LVDS outputs. > 5) SMA connector may be soldered instead of one of U.FL with CMOS > levels. It will add 4.5$ to the price. > 6) SMA connector with direct VCO output bypassing clock distributor. > It will add 4.5$ to the price. > 7) SMA connector for external clock source. This way onboard > oscillator should be disabled by resistors soldering or should not be > present. It will add 4.5$ to the price. > 8*) Oscillator could be changed to 0.5ppm. This will save you 7.5$. > 9*) VCO+PLL with clock divider could be changed to clock divider > and multiplier. In this case you won't be able to tune your clock > precisely, but you'll be able to generate, e.g. 13MHz, 26MHz and 62MHz > from a single oscillator. > 10*) Frequency range could be extended to 1.87-94.75MHz (and more > ranges higher) at the price of more phase noise. > 11*) For nerds only - unit may be used without onboard controller by > direct access to VCO+PLL pins. But this is roughly equivalent to > a VCO starter kit and obviously is not compatible with features like > SPI/USB/RS232 control, and can't be used with power from USRP. > 12) 1pps external signal may be used to tame the clock to external > GPS unit. It will be passed to ATMega's interrupt input, so you > should keep in mind that this will need a lot of software work for filtering > out jitter, generated by it. We don't plan to develop this software at > least now, but anyone who need this is welcome to take it. > > * These options is not immediately available because of changes in > components list. Some options need testing before we can offer units > with them. Some options available for small orders, some available > only for volume orders. And sure, you can solder them by yourself. > Mail me for details, if you're interested. > > There are two big options, which touches a big part of the unit and are > very much experimental. We can't guarantee that they will work, > but we think they will. :) > * TCXO with VCO+PLL could be replaced with VCTCXO with DAC. > DAC can be 12-bit linear or 16-bit delta-sigma. This will make it > about 20$ cheaper then default bundle if we produce it in volume. > The downside of this is that frequency range is much smaller and > more calibration is needed. > * GPS chip could be actually installed right on board to provide > 1pps signal. PCB is designed to be used with cheap EB230 GPS > Module and will add about 40$ to the price. But there are some small > limitations - you can't use RS232 output with it, only 5 output channels > are possible. Same notes on software as for 1pps input applies. > > We're working on detailed documentation and will make it available > as soon as possible. > > 1. http://www.conwin.com/datasheets/tx/tx236.pdf > 2. http://www.national.com/ds/LM/LMX2531LQ1515E.pdf > 3. http://www.national.com/ds/LM/LMK01000.pdf > > -- > Regards, > Alexander Chemeris. > -- Regards, Alexander Chemeris. _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
