RF filters and diplexers - Cross Country Wireless

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Cross Country Wireless have started making their range of RF filters and diplexers again after a break following the launch of their SDR-4+ receiver.

The RF filters include bandpass filters for 50, 70, 144 and 432 MHz, 144/432 MHz dual band filters and a double notch 144 MHz filter notching the UK paging frequencies.

The 144/432 MHz dual band filter is particularly useful with Yaesu/ Icom/ Kenwood dual band mobiles cutting out interference from and to local broadcast, TV, GSM and other amateur band signals.

The diplexers available are 50/70 MHz and 144/432 MHz.

Filters are £58.50 plus £5.00 post and packing.

Diplexers are £63.00 plus £5.00 post and packing.

More details including actual test sheets of recent filters and diplexers are available on their web site - http://www.crosscountrywireless.net/filter.htm

Diplexers - http://www.crosscountrywireless.net/diplexer.htm

Raspberry Pi sends live images from near space

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Dave Akerman has used a Raspberry Pi computer board as the flight computer on a High Altitude Balloon (HAB) and sent back live images from near space at an altitude of almost 40 km

The balloon, appropriately called PIE1, was launched from Brightwalton, in Berkshire on July 14, 2012. The images were transmitted on 434.650 MHz (300 bps, 600 Hz shift) in the amateur radio 70cm band using the Slow Scan Digital Video (SSDV) standard.

PIE1 reached an altitude of 39,994 metres and images were received as far away as Northern Ireland (that's over 500km, not bad for just 10mW on 434.650 MHz!).

The full story and pictures are on Dave Akerman's website - http://www.daveakerman.com/?p=592

Slow Scan Digital Video (SSDV) - http://ukhas.org.uk/guides:ssdv

UK High Altitude Society - http://www.ukhas.org.uk/

Yaesu FT1D Digital Handheld

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One of the most eagerly awaited products at Dayton Hamvention was the new Yaesu FT1D digital and FM handheld.

It has, for an Amateur Radio rig, a number of innovations:

  • A microphone that uses a mini-USB plug and has a built-in camera for low resolution (320x240) pictures,
  • An 80 character group short messaging facility
  • 9600 bps data transfer
  • Micro-SD card slot
  • E-GPS facility

Although the optional extra microphone has a camera there appears to be no way to display the pictures on the radio which some may see as reducing it's usefulness.

The use of 9600 bps with 12.5 kHz channel spacing (is it 10 kHz in Japan?) was a surprise. Some had expected it to support 5 or 6.25 kHz channel spacing with a resultant data rate of 4800 bps (digital speech using an AMBE vocoder only requires a 3600 bps data rate).

The modulation used is what Yaesu describes as C4FM otherwise known as 4 level FSK or 4-FSK and is the same as that used for Digital PMR-446 equipment. 4-FSK has advantages over other types of digital modulation such as GMSK.

Both ICOM and Kenwood have been producing 4-FSK equipment for the PMR market since 2007 so in some ways it's surprising that Yaesu beat them both in releasing an amateur version of 4-FSK.

As yet Yaesu hasn't announced any mobiles, base stations or repeaters so it appears that FT1D's can only talk to other FT1D's in digital mode.

The FT1DR/E brochure can be seen - http://www.radioworld.ca/product_brochures/amateur/yaesu_brochures/ft1d_brochure_front.pdf and http://www.radioworld.ca/product_brochures/amateur/yaesu_brochures/ft1d_brochure_back.pdf

N9XLC Blog on FT1D - http://n9xlc.blogspot.co.uk/2012/05/yeasu-ft-1d-redux.html​