New Schematic - Rev C.2

[NZ0I]

Now that a serial connection design has been proved out, I've gone ahead and added it to the transmitter schematic. Several other changes were also made to the transmitter schematic, and are described in today's blog post on http://openardf.org. Read it if you are interested. A .pdf of the latest schematic diagram is also linked to from that post.

With those changes I think that the dual-band ARDF transmitter design is now close to complete. The only tasks remaining: A faster USB charge circuit needs to be explored; Also, it would be good to add support for a GPS module, so that self-correcting precise time could be maintained by the transmitter.

It occurred to me recently that the ability to "clone" transmitters (and receivers too) should not be too difficult to implement. By cloning, I'm referring to having one transmitter transfer its non-unique settings to another transmitter over a serial connection. The "master" transmitter would synchronize the clock of the slave transmitter it is connected to, and transfer frequency, sport event, start-time, and call-sign information to it. The slave would retain its unique data, such as "fox id", or perhaps the master could assign a unique fox id to any transmitter found to have a duplicate setting. Cloning should, I think, greatly reduce the need for a Control Head, or a PC, when configuring transmitters.

It has also become apparent that a GPS module will require a more capable processor than the ATmega328P, at least if position information is to be utilized. Time syncing to a GPS module shouldn't be too software-intensive, but calculating traversed distance, direction-of-travel, cross-track error, and other useful data from NMEA 0183 position data is going to take up significant room in flash memory. Also, it would be best to use a processor with two UART serial ports, so that one could be dedicated just to GPS, and the other to Linkbus and PC communications. The ATMEGA1284P looks like a good candidate, and only costs a few $$ more than the '328P. I'll look into how difficult it would be to move to the more powerful processor before the first prototype build... if it is too much work then it might have to wait until a future receiver upgrade cycle. (The transmitter shouldn't require the upgrade, since it only utilizes the GPS time, and doesn't need to make use of the position information.)

[Gerald Boyd]

Thanks.

Cloning idea looks good.

Downloaded the latest schematic and will look it over.

Jerry

Sent from my iPad

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