FUNcube Dongle

Folks

Production FCDs thus far have all been shipped with firmware release 18b. This has been through months of proving both before and after production release.

This firmware has been in existence since October 2010, and there have been four firmware releases since then, all of which are designed to be backwards compatible.

This means that should you decide to install the latest, 18f, firmware, it should not break anything you were doing already on an earlier version of firmware, and if it does, let me know!

The newer firmware updates have been made available to provide a much more comprehensive API for third party deveopers, so you will quite likely find that there will be prerequisites from host software for certain firmware versions.

Installing new firmware should only take a minute or so, and as well as updated firmware there’s also a guide in the downlaod section.

Howard

Folks

There was a recent question about a block diagram for the FCD, and I must admit I thought there was one here already on the site but I can’t find it – there was certainly one over on funcube.org.uk at some point. Anyway, here it is, with a pitcure of a board.

Howard

Folks

I am indebted to David Barber’s work on providing a number of guides for the FCD on the downloads page.

Today we’ve placed some updated WRplus documents there.

Thanks again to David!

Howard

Folks

I had a question recently about the close-in phase noise around the zero IF, where many FCD and Softrock users will see a peak in the middle of passband. Although you can correct for DC offset, phase noise is by definition unpredictable but it can be characterised. Here are some pics of the phase noise, firstly in a full 96kHz span and secondly zoomed in to a 4kHz span.

Howard

(*** see updates here and here)

As you are aware one of the key features of the FCD is its wide frequency range of operation. While this is great, the compromise with wide band receivers are that they can suffer from desense from out of band signals.

Although the FCD has programmable and fixed front end filtering, at VHF the filters are quite wide and if you’re in a strong signal area, popping in a low loss front end filter will help here.

I’ve built three 2m band pass filters based on the design here.

What I’ve discovered is that you really do need to use the PCB layout with the through hole links, and you must use screening around the unit either with PCB material or for example some brass shim. Without these considerations I found the filter lossy and difficult to tune.

In addition, I found the inductors as specified made the filter LF at 116MHz, so a fair bit of stretching was needed. Luckily I have a VNA in the kitchen lab to do this although you could have a go yourself, tuning for maximum signal on a beacon.

I managed 1.2dB loss with about two or three minutes of coil massage. Probably I could tweak it a bit more given time.

The pictures show the filter and its response. The span is from 50MHz to 250MHz. Thus, in the UK, it might not be the best if you are suffering close in pager interference around 138 or 153MHz where notch filters will provide better immunity.

Howard

Folks

While producing the posting labels on Saturday we discovered that Paypal has now removed their Airsure option, so we have used their International Signed For for all non UK deliveries. The alternative was to manually cut and paste each line of each address petween Paypal and RM’s systems, and that was clearly unsustainable.

The target (although not guaranteed) times for International Signed For are three working days to Western Europe, five working days to Eastern Europe and seven working days for the rest of the world.

Deliveries to UK destinations are still next day Special Delivery 1pm.

If your item has not been delivered by the above target times, I will gladly provide tracking numbers.

All items were delivered to the Post Office on Monday morning.

Many thanks, Howard

Folks.

I placed 120 units in the Paypal inventory for the 10pm sale, although Paypal oversold again so a total of 135 units were sold, although one was cancelled, so it’s 134 really.

The oversold inventory expired at 22:00:49.

We had a total of 140 available, of which 60 were built by yours truly and 80 by my new manufacturer. Those 80 units arrived from the manufacturer on Friday at 2pm. I had tested all of them by 6pm. 25 had faults, and I’d fixed 12 of those on the fly during the testing as they were simple faults. The remaining 13 faults were fixed on Saturday morning. I then set to on the HPF rework on all those 80 units on Saturday afternoon. This was completed by Saturday night, however they were not tested until this morning (Sunday). Complete testing and checkout of all 140 units was completed today (Sunday) at 2pm. There were no write offs.

From Saturday morning until Sunday evening, I had one relative full time performing dispatch, and on Saturday afternoon I had another passing relative preparing the enclosures (labelling, drilling etc). They’re young, and are not easily offended by the offer of cold hard cash. Normally over the weekend sales I do the labelling with graciously accepted help from the OH, and help out with dispatch, but the later arrival of the units from the manufacturer meant I was busy getting the hardware itself ready.

Each unit is system tested three times. Firstly immediately after construction (when the bootloader is also installed), secondly after the HPF rework and thirdly after placement in the enclosure. When rework is done in large batches such as in this last batch, the second and third tests are performed at the same time by testing the unit out side of the enclosure and if it tests well it is immediately placed in the enclosure and tested in situ there.

I’ve found in tests after the HPF rework has been installed often results in having to replace the LNA as its sensitivity seems to be impaired by a dB or two. This appears to be due to the thermal cycling. This occurs in abut 10% of boards.

In addition, the tuner chips need replacement about 5% of the time due to I/Q imbalance being out of spec.

I found an exceptional number of PCB faults too on these latest boards which is very disappointing. About half a dozen breaks in tracks that must have been caused by faulty photographics when looked at under the microcscope. Unless you’ve seen them before, debugging these is a very lengthy process often with numerous blind alleys.

There also seems to be a problem with some 1nF caps I am using that seem to frequently suffer cracks. I will change the manufacturer for the next runs.

Here is the feedback to the manufacturer on the 25 or so units that failed.

xx1 Crystal 1000ppm HF, also may be coincidence, looks like may not have been soldered properly on one lug, fixed
xx2 USB connector plastic deformed, I assume something happened during reflow, it would not physically mate, replaced connector, fixed
xx0 IC8 pin 6 lifted, fixed
xx3 high phase noise, intermittent, replaced IC3, fixed
xx8 Clock low p-p swing, replaced IC2, fixed
xx9 deaf, replaced C1 (cracked), fixed
xx6.1 I/Q imbalance 20dB, replaced IC3, fixed
xx6.2 deaf, replaced IC4 and C1 (cracked), fixed
xx7.1 stuck in bootloader, replaced IC10 3.3A reg, fixed
xx7.2 deaf, replaced IC4, fixed
xx0 codec data track broken (PCB fault), fixed
xx2 stuck in bootloader, track broken pin 32 IC3 (PCB fault), fixed
xx3 codec data track broken (PCB fault), fixed
xx3 I/Q imbalance 10dB, replaced IC3, fixed
xx4 USB connector D- line connection lifted, fixed
xx3 I/Q imbalance 20dB, replaced IC3, fixed
xx4 I/Q imbalance 20dB, replaced IC3, fixed
xx6 I/Q imbalance 20dB, replaced IC3, fixed
xx8 deaf, replaced IC3 and C1 (cracked), fixed
xx4 codec data track broken (PCB fault), fixed
xx5 stuck in bootloader, IC2 solder bridge pins 7 & 8, fixed
xx8 I/Q imbalance 20dB, replaced IC3, fixed
xx2 stuck in bootloader, solder bridge on IC2 pins 17 & 18, fixed
xx7 totally deaf, lifted PCB track IC3 pin 8, fixed
xx9 stuck in bootloader, IC2 incorrectly oriented, fixed

Howard

Folks

The next sale will be on Friday 4 February 2011 at 22:00 UTC. Sorry, sold out again. The next sale will be in the next couple of weeks, I’ll let you know on the site exactly when it is.

Howard

Folks

This year is not what I expected. I’ve worked for myself for twenty years, and until a few short weeks ago my working life and career has always been providing design and troubleshooting services for financial trading systems.

My last contracted engagement finished just before Christmas, and I was expecting to simply pick up another contract in the new year.

However the response to the FCD has been so phenomenal, I have barely had time to search for that new position. Whereas usually I’d be spending my time polishing up my skills and searching for that next role, instead it’s been spent making and supporting FUNcube Dongles.

The thought of working from home historically has filled me with dread and lack of productivity as you are surrounded by all those distractions. So until now I had never ever worked from home. Turns out, those distractions are there, but my own self imposed target dates for batches rather focuses the mind.

What’s been great is that I had my first walk in personal customer a couple of days ago! You may remember that there was a failure mode in a few of the very first FCDs after the HPF rework where a 1nF cap cracked. My caller had it fixed there and then. So, if you happen to be in Central London and need good old fashioned personal service for your FCD, let me know.

Howard

OK, so I got up at 5:30am today and it’s midnight now, but in an effort to get as many boards ready as possible for the next sale (around 4/5/6 Feb) I had a marathon session today. 3,000 parts is 30 boards! OK, so they’re not tested and there’s no connectors or HPF rework on them, but considering I started off doing a third of this rate only a short six weeks ago, I’m pretty impressed with myself, but my head is now officially jelly.

Hopefully this will all be a thing of the past next week if the new assembler turns up trumps.

Time for a G&T.

Howard