ERASynth: Open Source RF Signal Generator - Request for Feedback - Page 1
Forum section: electronics / general

author: edensrock
author_rank: Contributor
timestamp: May 14, 2017, 06:19:10 pm
content: Hi everyone,We are running our crowdfund campaignERASynth on CrowdSupply. We would like to see your valuable feedback and recommendations. Your comments are very important since we are still in the process of taping out last revision of the board.Thanks in advance.edensrock

author: Rick
author_rank: Frequent Contributor
timestamp: May 19, 2017, 12:17:18 am
content: You need to send a free sample to Dave and he might review it if he is in good mood... Cheers.

author: KE5FX
author_rank: Super Contributor
timestamp: May 19, 2017, 01:08:41 am
content: Quote from: edensrock on May 14, 2017, 06:19:10 pmHey, this really does look cool. -125 dBc/Hz at 10 kHz from a 1 GHz carrier out of an ADF4356 is pretty impressive.It's good to see so much technical detail up front. Good luck with the Kickstarter!Some brief thoughts:- If you use a DDS anywhere in the design, consider adding an LF output path for it. It'd be nice to offer 9 kHz-15 GHz coverage, or even lower. Not a huge deal but occasionally useful.- Offer a version on your Kickstarter without the OCXO. Many of your customers will have their own stable 10 MHz references available, so it's a waste of money to include OCXOs at the instrument level.- Lack of ALC is probably the biggest Achilles' heel I see. Calibrated and leveled output power is pretty important. I'd suggest prioritizing this in the next spin.- LMX2594 just came out. Could be worth looking at, but it sounds like you're getting similar performance from the ADF4356 already, so maybe not.

author: edensrock
author_rank: Contributor
timestamp: May 19, 2017, 08:30:17 am
content: We are planning on sending one unit to Dave for Monday mailbag once we finish the final revision.Quote from: Rick on May 19, 2017, 12:17:18 am

author: edensrock
author_rank: Contributor
timestamp: May 19, 2017, 09:24:19 am
content: Thank you KE5FX for insightful suggestionsWe are not getting -125dBc/Hz PN out of ADF4356. We used ADF4356 + LTC6945 combination as the main PLL plus HMC830 as the tunable reference generator to get -120 dBc/Hz in our current revision. At that time, LMX2594 wasn't around (we started this project in August 2016). Just before the launch of our campaign, TI released LMX2594, and it was scary good (*). We were going to do one final revision anyway, so we decided to use LMX2594 as the main PLL as well as the tunable reference generator. We purchased two copies of the LMX25945 the eval board and tested to see everything was inline with the datasheet, and it was. Here is the block diagram of both current revision and the final revision of ERASynth:http://erainstruments.com/erasynth/erasynth-current-block.pnghttp://erainstruments.com/erasynth/erasynth-final-block.pngThe phase noise graphs shown on the campaign page were taken with our current revision. Hence, tunable ref is HMC830, VCO is the VCO of ADF4356 and Int-N PLL is LTC6945. You may see the PN graphs here:https://www.crowdsupply.com/img/35ff/erasynth-pn-10ghz.pnghttps://www.crowdsupply.com/img/f040/erasynth-pn-1ghz.pngThese are respectable numbers to squeeze out of ADF4356. Yet, we are targeting another 5 dB improvement (in the pedestal region) over these numbers in the final revision.We will be using a DDS to go down as much as possible in the plus version in the final revision, we are planning on using AD9913. We will consider adding an LF output. It will require an extra SMA connector, which may not be possible. We will see what we can do when we do the final layout.There is a model on the campaign without the OCXO, but it only goes up to 6 GHz. However, both of the ERASynth models also accept external 10 MHz reference signal. If you have your own more stable 10MHz signal you may use it. Default inclusion of the OCXO just increased the cost a little bit, but people who doesn't have their own ultrastable timebase will appreciate it.As for ALC, it is really beyond the scope of this project. Open loop calibration doesn't mean that the amplitude accuracy will be all over the place. At the moment, we are doing tests to see how our open loop calibration performs. We will publish the results as an upcoming campaign update. Please followour campaign pagefor updates.(*) LMX2594 has the best flat phase noise FOM -236dBc/Hz in the industry at the moment. However, LTC6945 is still better when it comes to flicker FOM (Flicker FOMs: LTC6945=-274dBc/Hz vs LMX2594=-269dBc/Hz).Quote from: KE5FX on May 19, 2017, 01:08:41 am

author: hendorog
author_rank: Super Contributor
timestamp: May 24, 2017, 10:03:54 am
content: Cool project and impressive specs!My ideas (based on the final block diagram):Use the/a DDS for the < 10MHz output, which frees up RF Out A to be differential - so now you can use a balun on RF Out A to reduce the 2nd harmonic on the <6GHz output.Expose the SYNC pin of the LMX2594 so that multiple devices can be made phase coherent.Expose the RAMPCLK, RAMPDIR and MUXOUT (for Ramp Status) pins too.

author: awallin
author_rank: Frequent Contributor
timestamp: May 24, 2017, 02:00:23 pm
content: I'm too lazy to read the fine-print myself, can someone clarify what happens with a Crowd Supply project if I back it but then the supplier fails to deliver?Any guarantees at all that I will get anything if I now feel like I have about $750 extra in the bank?

author: edensrock
author_rank: Contributor
timestamp: May 24, 2017, 03:39:44 pm
content: hendorog,Thanks for the valuable feedbackWe are going to use the DDS but probably cannot do the balun. I am not aware of any single balun (with reasonable cost) that can cover 10 MHz to 6 GHz. Besides, our tests on the LMX2594 eval board showed good results for 2nd harmonic. The -10 dBc typical value given in the campaign page was mainly due to 3rd harmonic.We are going to consider to expose SYNC and MUXOUT pins. For ramping we have a multi-purpose trigger input, same functionality can be implemented using the trigger pin + GUI.Quote from: hendorog on May 24, 2017, 10:03:54 am

author: edensrock
author_rank: Contributor
timestamp: May 24, 2017, 04:16:45 pm
content: awallin,As far as I know Crowd Supply is the only crowdfunding site with100% delivery rate. We -as ERA Instruments- have no intention of destroying that reputation. We already have a working prototype and will do our best to deliver the best possible product to our backers. Although the prices shown on the campaign page might seem high for a crowd-funded project, we are not really making any profit in this project. RF components are not cheap. Just the main PLL IC on our final BOM (LMX2594) costsmore than $50(and we are using two of these in a single ERASynth).Then, why are we doing this project? We have been working as consultant to some local defense companies in Turkey for several years. This project is our first attempt to create our own business. We would like build a good global reputation. Not delivering would defeat the whole purpose of doing it.Quote from: awallin on May 24, 2017, 02:00:23 pm

author: hendorog
author_rank: Super Contributor
timestamp: May 24, 2017, 08:42:43 pm
content: Another idea - I'm sure you have already considered this, but how about another option without the case?I know performance would suffer but it should allow a decent price reduction, and so get the price down enough to engage DIY/maker types.I was thinking a reference design for a 3d printer could be published on thingiverse. Printing and internal shielding done with copper tape by the purchaser.The pricing of the ERASynth is just a bit higher than what a maker would go for.

author: KE5FX
author_rank: Super Contributor
timestamp: May 25, 2017, 01:09:06 am
content: Quote from: edensrock on May 24, 2017, 03:39:44 pmYou could use a Mini-Circuits TCM1-63-AX+ or TCM1-83-AX+, but if the goal is to cut down on harmonic output, one of their inexpensive ceramic filters would make more sense. The only real advantage to the balun would be a couple dB more power output.Harmonic content can actually be kind of useful with these chips, so I don't know that I would go out of my way to suppress it. The user can always add a filter of their own.

author: hendorog
author_rank: Super Contributor
timestamp: May 25, 2017, 02:08:32 am
content: Quote from: KE5FX on May 25, 2017, 01:09:06 amYeah those were the baluns I was thinking of. Whether they are resonably priced is open to discussionThe even harmonics should theoretically be perfectly cancelled as they are in phase at the balun input.Also the 2nd harmonic of the < 6ghz fundamental under discussion wouldn't be useful either as there would still be the 6-15ghz output available.But of course no point given the odd harmonics dominate.

author: edensrock
author_rank: Contributor
timestamp: May 25, 2017, 07:07:04 am
content: KE5FX,These are nice baluns but as you said several lower cost (such as LFCN series) filters would make more sense. As Jorgesen and Marki pointed out inMarki Microwave's Balun Primer, the max rejection we can get out of these baluns is about 15 to 25dB with the values given for the phase and amplitude imbalance values. We can easily get more from inexpensive filters. If we decide to use filters, it will also require using switches since we cannot use a single filter over a multi-octave range. That will further increase the BOM and complicate the board. Just as you said we think it is best to leave it to user to reject the harmonics with their own external filters.Quote from: KE5FX on May 25, 2017, 01:09:06 am

author: edensrock
author_rank: Contributor
timestamp: May 25, 2017, 07:21:23 am
content: hendorog,We have seen other projects where only the board (even unpopulated boards) are offered as options. We didn't do that because -as you said- performance would take a huge blow without the case.Quote from: hendorog on May 24, 2017, 08:42:43 pm

author: orin
author_rank: Frequent Contributor
timestamp: June 07, 2017, 05:09:33 am
content: edensrock,This looks really nice. I'd wondered about the concept of using the modern RF chips to make a sig gen... and you've gone and done it!I've put my 'order' in and hope you make your target!Orin.

author: edensrock
author_rank: Contributor
timestamp: June 07, 2017, 06:16:55 pm
content: Orin,Thank you very much for your support. We are now at 97%. Almost thereQuote from: orin on June 07, 2017, 05:09:33 am

author: piranha32
author_rank: Unknown
timestamp: August 30, 2017, 07:10:38 am
content: edensrock,What is going on with the project? The last post on EEVBlog forum was in the beginning of June, the last post on Crowdsupply, in which ERA team promised frequent updates, was on the last day of the campaign, and not a word since then. Is the project still alive? Are you planning to deliver ERASynths to backers?

author: Neganur
author_rank: Unknown
timestamp: August 30, 2017, 07:25:41 am
content: You can look at the time plan on the crowdsupply website.I think it says September 21 is when they plan to ship to backers.With 25 weeks lead time on some components and no visible buffer time planned for 'things that can go wrong'I'd be surprised if you'll get it this year

author: piranha32
author_rank: Unknown
timestamp: August 30, 2017, 04:09:49 pm
content: I am familiar with their schedule and, based on my experience from other crowdfunded project, I don't expect the units to ship on time. I'm not blaming anybody, I realize that it's very hard to set specific date of delivery ahead of time.However, the sudden drop of updates on the day when the funding campaign closed, from a team who have been very active and very open in their communication to the investors, and who promised frequent updates in their last message, is quite unsettling.

author: ezalys
author_rank: Frequent Contributor
timestamp: November 04, 2017, 06:53:11 pm
content: Why have you added wi-fi to this unit? I can't possibly understand why a device that has been designed to output a pure monochromatic signal has another radio stuck in it somewhere. I'd be a fan of adding ethernet, but definitely not wi-fi.

author: chriswebb
author_rank: Unknown
timestamp: April 11, 2018, 05:23:34 am
content: Update! looks like they have sent the products to the crowdsupply facilities in Portland:https://www.crowdsupply.com/era-instruments/erasynth/updates/erasynths-on-their-way-to-crowd-supply

author: jhenderson0107
author_rank: Regular Contributor
timestamp: April 19, 2018, 04:14:18 pm
content: Got my ship notice this morning. Looking forward to using this in numerous projects.

author: piranha32
author_rank: Unknown
timestamp: April 20, 2018, 11:09:09 pm
content: I've just got my unit. Looks super solid and sturdy. Powers up, blinks the lights. Next challenge: finding the documentation how to connect

author: piranha32
author_rank: Unknown
timestamp: April 20, 2018, 11:13:46 pm
content: Quote from: piranha32 on April 20, 2018, 11:09:09 pmPDF with user guide linked on crowdsupply page does not work, but all docs are available on github:https://github.com/erainstruments/

author: orin
author_rank: Frequent Contributor
timestamp: April 21, 2018, 04:54:58 pm
content: Mine arrived yesterday.I could not get the wifi hotspot to work correctly. It showed up, but connecting to it took a long time and once connected, the UI took minutes to show up and was unresponsive.I used the serial interface to switch to wifi station mode and it seems to be working OK now.

author: piranha32
author_rank: Unknown
timestamp: April 21, 2018, 05:52:09 pm
content: I also noticed that when connecting from laptop it took a long time to connect, and then the web page tried to download a javascript library from code.jquery.org. It of course will not work, because there is no internet connectivity. OTOH when connecting using tablet everything worked flawlessly. The page is clearly optimized for mobile devices, so I guess they did very little testing with desktop browsers. I have no idea why connecting over wifi from a laptop takes so long.Another thing that I could not get to work is frequency sweep. Regardless of settings, ERA always wants to sweep from 1GHz to 2GHz

author: orin
author_rank: Frequent Contributor
timestamp: April 21, 2018, 07:30:30 pm
content: Quote from: piranha32 on April 21, 2018, 05:52:09 pmAs a hotspot, I tried both from an iPhone and a Mac... I didn't try from a PC or Android. Good catch on the jquery download. I hadn't bothered trying to work out what was going on since the initial connection was so slow.I'm now testing it with an 8568A spectrum analyzer and 5370A counter, controlling it from a Win7 laptop and wifi in station mode. Seems to be about 3Hz low at 10MHz with the counter fed from a GPSDO. Looks to be within milli-Hertz if I use a GPSDO as an external reference. The OXCO might need some time to settle and the temp in the 'lab' is only 17 deg C at the moment.All seems good up to 1.7GHz - the limit of the 8568A. Now I need an SA that goes higher.Edit: OXCO is currently drifting higher at about 0.1 Hz/hour according to Timelab.

author: piranha32
author_rank: Unknown
timestamp: April 21, 2018, 09:29:20 pm
content: On GPS-locked E7495A and ERA tuned to 10MHz TCXO seems to be spot on, surprisingly OCXO appears to be 14Hz low. The narrowest RBW is 30Hz, so it's not conclusive, but I did not expect such a big difference, especially for OCXO. Unfortunately I don't have GPSDO to lock ERA, so I can't tell how much of this difference comes from the reference XO, and how much is due to poor resolution of the instrument.Update:The same holds for ERA set to 2.5GHz. TCXO is much closer to the set frequency than OCXO. Frequency locked to the OCXO is ~7kHz low, and TCXO is ~1.3kHz over. If it wasn't for frequency drift while OCXO starts up, I would tell that the labels got mixed up. Also, the frequency in steady state seems to be constantly drifting by single Hz, but again, I can't tell how much of it comes from the SA itself.Last, but not least, refreshing the diagnostics page during OCXO startup shows all three PLLs as locked through all the time as the crystal heats up. I did not expect the Xtal PLL to respond that quickly to sudden changes of ref frequency.

author: orin
author_rank: Frequent Contributor
timestamp: April 22, 2018, 06:06:52 am
content: Well, a little digging and the Crowd Supply page claimed the OXCO is an AOCJYR. There is a datasheet on Mouser:https://www.mouser.com/datasheet/2/3/AOCJYR-10.000MHz-M5625LF-372124.pdfInitial frequency tolerance of +/- 0.5 ppm and a shift due to reflow soldering of +/- 1ppm so I'm well within that limit. Also, the 24hr +/- 1deg C holdover stability of +/- 4ppb is "After 30 days of continuous operation". These things like to be kept powered up!So, nothing untoward really, but I'll make an enhancement request of being able to specify the actual OCXO/TCXO frequency so the firmware can make a correction for these small offsets... unless it's already there and I missed it.If ERA Instruments are listening in, I'd also ask that the LMX2 PLL LOCK diagnostic be greyed out if operating at a frequency at which it's not used. (I checked the firmware source, its disabled 30MHz and below). Otherwise, it's misleading to show "Not Locked" when running at 30MHz or below.Oh BTW, it looks a lot nicer in person than the latest pictures on the Crowd Supply page and is very nicely built. I look forward to getting rid of the huge Wavetek SG that sometimes refuses to phase lock right at the frequency I want to use!

author: edensrock
author_rank: Contributor
timestamp: April 23, 2018, 09:57:47 am
content: Hi orin, piranha32, jhenderson0107, chriswebb and ezalys!Thank you all very much for your valuable feedback. We are indeed listening in, just haven't been logged-in for a while. We take all of the feedback seriously.@ezalysQuote from: ezalys on November 04, 2017, 06:53:11 pmWi-Fi module can be disabled using the web GUI or the PC GUI. If software disabling doesn't work for you, you can open the case and remove the ferrite bead L54 on the board. That will permanently power off the Wi-Fi module.@piranha32Quote from: orin on April 21, 2018, 04:54:58 pmSorry about the broken links. The links somehow are working for me. I will update our campaign page with a link to our GitHub repo's root folder (https://github.com/erainstruments/).@orinQuote from: orin on April 22, 2018, 06:06:52 amThere is no frequency offset feature at the moment. We will try to implement it in the upcoming firmware fix.

author: orin
author_rank: Frequent Contributor
timestamp: April 23, 2018, 05:18:10 pm
content: OCXO 'warmup' so far.Edit:Counter is an HP 5370A using a Trimble Thunderbolt GPSDO for its reference.'Warmup' isn't really the right word - 'aging' or 'drift' would be better.

author: KE5FX
author_rank: Super Contributor
timestamp: April 23, 2018, 08:21:20 pm
content: Quote from: orin on April 23, 2018, 05:18:10 pmThat should settle down nicely in a week or so.Looks like the manufacturer doesn't do any aging before shipment. Probably not unreasonable when paying around $100 for a factory-fresh OCXO.

author: orin
author_rank: Frequent Contributor
timestamp: April 24, 2018, 07:08:35 pm
content: Took it to 15GHz last night using a 5342A counter. Things didn't look good over 14GHz until I realized the 15dB Mini Circuits attenuator* I keep on the counter's input was only rated to 6GHz! All was fine once I reduced the power and removed the attenuator. This was as much a test of the counter as the ERASynth. When I got the counter, it was sold as not counting on any range - but as far as I can tell, it counts just fine.*It's very easy to blow the sampler on the input of these counters, so I keep the attenuator on it for protection. The samplers are of course, unobtanium.

author: 9aplus
author_rank: Regular Contributor
timestamp: July 02, 2018, 10:34:07 pm
content: Hi to all....just to report that I finally managed some of my free time to make some testMy unit sn:015 ERASynth+ was delivered to UK site approx 5 weeks ago.Have find out that USB PS declared for 2 A can not run the unitbut two USB ports from my notebook combined in one makes good enough PS source.(Have another one declared for 2,4 A for second test tomorrow.)PC was able to connect to wi-fi AP mode on first attempt, also managed to getsome signal out but not on all freq... for example on 145 MHzIt seems that some firmware update or direct serial port use is necessary.To be continued...

author: 9aplus
author_rank: Regular Contributor
timestamp: July 03, 2018, 07:53:52 am
content: Unit is happy with 2.4 A 5V PS sourced from one tabletSweep is running...

author: 9aplus
author_rank: Regular Contributor
timestamp: July 03, 2018, 09:24:32 pm
content: Direct serial port use working ok.Win PC application working too.Firmware upgrade is must...That is on my to do list for tomorrow,Arduino IDE / duo and ESP support already installed today.

author: KE5FX
author_rank: Super Contributor
timestamp: July 05, 2018, 01:20:34 am
content: What tablet brand/model is this?

author: 9aplus
author_rank: Regular Contributor
timestamp: July 05, 2018, 07:28:04 am
content: Lenovo MIIX300 10" tablet with additional keyb...Original PS have USB port, so just another cable.Here, still preparing firmware upgrade, I am RPI guy, not familiar with Arduino duo.So trying to be 100% sure what I am doing, in attempt to not brick ERASynth+

author: 9aplus
author_rank: Regular Contributor
timestamp: July 23, 2018, 09:47:39 pm
content: On first try of firmware upgrade I have bricked my unit,but after some advice through opened issue on:https://github.com/erainstruments/erasynth-firmwareSecond upgrade went well...Through terminal commands unit is now working like charm.Both web and Win application need some further debuging.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 03, 2020, 12:55:49 am
content: EraSynth Micro Damaged Output