Τετάρτη, 17 Ιουνίου 2015

RF Sniffing on HF bands

It was some time ago when I discovered PSKreporter and reversebeacon networks. It's all about reporting what you listen on the air to check about band propagation any given time and place. Multiple reporters exist, and most digi mode ham radio software is now reporting when you use it.
I like PSK reporter mostly because of the way they visualize everything. It's also a nice way to test your equipment, antennas, pre-amps by comparing the stations and the range you can hear.
A few months after reporting PSK and JT65 and burning my FT-920 on a thunderstorm, I decided it was time to move on. Multi band reporting using a single SDR and software was intriguing but needed some setup. The main set back, was that only Windows software exists for CW skimming and there was no way to use my existing PC's and SBC's. A few days ago I switched on my old Windows XP machine and installed all the required software, only to find out that everything was working flawlessly as described by the software authors!
A great thanks to OL5Q for providing the USRP library software for CW skimmer! Now I can use my USRP1 to listen and report from 4 HF bands simultaneously! I've picked the 20,17,15,12 meter bands mostly because my Cushcraft R5 antenna is made for those bands. Now my call-sign appears on the global top 10 chart of reporters with more than 100 different countries reported in one single day. Next is to be able to report digital modes also, and more HF bands.

I've also tried using RTL-SDR USB sticks with up-converters but the issue was that the up-converter clock was not stable enough to decode JT65. I've used both No-elec and SV1AFN up-converter. After talking with Makis, he confirmed that the clock was not for such use, and I've purchased a surplus stock 200MHz crystal from ebay to upgrade my up-converter. But, to use RTL-SDR you need one device for each band due to the "narrow" bandwidth they have, so you need to have RF power splitters for each stick. Moreover the USRP has a 12bit ADC instead of 8bit resulting in better dynamic range of the receiver. At the moment I use the LNA4HF  but I've also ordered the J310 pre amp from SV1AFN to compare them. 

Πέμπτη, 4 Ιουνίου 2015

Farnell vs Mouser

Every radio amateur should have at least one in his hobbyist career wondered where to order parts from. Here in Greece, in the city I live, there are NO local stores that offer parts besides the most common ones.
So when I decided to build the mcHF, I have had my BOM's ready to upload them and get a price quote for the parts. The amount was respectable, about 200 Euros so I needed to find an economic solution. Since I was in Europe Farnell was the obvious choice, in terms of speed of delivery and customs. However due to an incident with a Farnell salesman I took the other way, across the Atlantic ocean.

Farnell has a "tool" to upload the BOM and give you a price quote. To my surprise this is NOT an automated procedure! You just upload the BOM and then wait until someone does something for it!
The same day I get the following reply on my e-mail"

"Would you like to place the order for the attached parts"

Besides the fact that there is no question-mark on this sentence, if I was to order I would have ordered, I wouldn't be asking for a price quote! The guy that replied to me was the "International Sales Co-ordinator" 

Anyway I decide to be polite, and reply to him that I would like to know what would be the total cost to decide if I'm going to place the order or not.

A few minutes later I get this fantastic reply!

If you visit our fantastic website, www.*******.com

Scroll down and click the farnell export link

We have a great search engine with prices, technical data sheets etc

Imagine that! There is a web site that has the technical data sheets and prices of all the parts! And it's also a fantastic one!
Then I realized that I did not want to do business with the English guys. I went through the process of building a BOM for Mouser, I uploaded it to their web site, and in seconds I had my price quote! There were some parts out of stock, but I easily replaced them with the suggested alternative ones. Mouser had FREE shipping, and guess what else! No need to wait for customs clearance and to pay extra money on custom fees because they have settled everything for you! They use a special freight service in co-operation with FedEx in which they import the parts to Europe for you. Also billing was made from within the EU and if you have a business VAT number withing the EU, you can exempt VAT. The parts arrived within a week, and generally their customer experience is amazing.

So, the Americans beat us in this...