Ultra Sniffer Status

Update: 27 October 1998

New CPU design

The Ultra sniffer is undergoing a revision. We are upgrading the original 68HC05K1 processor to a PIC controller which will give us much more program memory, and well as on chip ADC and PWM channels. An extra bonus is the on chip Uart, which we will be able to access through the multi-purpose 3.5mm jack.

Though the processor will still be an OTP (One time programmable) device, we will also have a serial EEPROM on the board which will allow limited user configurability. The number of channels and the number and order of modes can be decided by the user, and changed using the serial port and a PC program.

Changes are also being made to the amplifier chain. The main audio amplifier will now be a discrete design which will take less current, and have the advantage we can run it "backwards" to use the speaker as a microphone. The FM-link circuit will only be powered up when a plug is inserted, saving current when using the speaker.

The RF card has to have significant changes now in since Motorola have decided to prune the MC3362 device. The MC13135 chip is the planned replacement.

It will be possible to still use the original RF card with the new CPU card. Slightly more close up attenuation will be possible with the new sniffer because the GAIN response can be pushed into the non-linear region. To compensate we will have a lookup table in the new EEPROM to ensure the range steps are consistant.

The connections between between the CPU and RF cards has been lined up so that an in-line plug/socket pair can be used to connect the two cards together rather than the existing wiring loom. This will make construction a great deal simpler and less prone to error.

New Features

New features over and above the last design:

Uart to allow User configurability. Access through the 3.5mm multi-purpose connector.
Many more channels possible. Programmable Base frequency.
Less current drain for more sniff time between charges.
Intelligent Nicad discharge / charging control using the on-board uP.
Repeater Offset possible in FM mode.
Better FM overload performance.
ARDF Tx mode. Program in the number of transmitters used and the sequence number. Practice ARDF.
More close up attenuation. Faster Ranging.
Configurable volume control.
Possible future scanning ability.
Better Tx audio. No seperate microphone required.
More code space for more features in the future
Less wiring.
Better IMD handling with the new Motorola MC13135 chip.

Where it's at

A revised CPU card layout has just been completed. This layout includes a number of changes that were made to the prototype CPU card last reported. Some clever circuit re-arrangements have been made that allow user volume control of each mode of output (speaker/headphones) for each audio source shared with the transmit ALC control. Our confidence level with this layout is high.

The RF card has had to have significant changes now since Motorola have decided to prune the MC3362 device. A prototype RF card with the new MC13135/6 device has been built and evaluated (and is still in fact in use in one of my own sniffers). The new RF card layout has recently been completed also.

The two new PCB cards will be included on a panel that will be manufactured shortly by the Victorian ARDF group (the panel includes the new ARDF transmitters). Enquires about ARDF 2m/80m transmitters can be directed to the Vic ARDF Group.

David, VK3XAJ is proceeding with the software design.

Parts ordering has commenced and many parts are now in stock. This is all a "spare time" project, so the more incentive and encouragement we get the quicker it will all happen. You can pre-order a new style kit, or at let let us know if you are interested.

Kit suppliers wanted

We're looking for people or companies to source parts and put together kits for their local market. Some people also want to buy fully assembled units. We can supply the PCBs and the programmed OTP processor. A kit made up of parts sourced in the US should be much cheaper than a kit sourced here posted to the US because most of the parts are made by US manufacturers anyway.

Most of the parts used are surface mount. The resisters and capacitors are mainly 0805 size. Parts are variously made by Motorola, C&K, National Semiconductor, Murata, PIC and others. Let us know if you are interested.

I have send out new parts lists to those people who have already expressed an interest in taking on this task.

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