There are omni directional antennas with at least +5 dBi gain, maybe more.

I just got an advertisement for a new TI chip “CC2591″, maybe you could use that?
http://www.ti-estore.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=CC2591EMK

I have no idea if it’s legal to boost the output power 100-fold, you’ll have to check that yourself!

Another part of the Spektrum DX puzzle.

With respect to the pinouts for the CYWUSB6934 see http://download.cypress.com.edgesuite.net/design_resources/datasheets/contents/cywusb6934_8.pdf. SPI interface: Pin 22 = slave select, 23 = MOSI, 24=MISO, 25=SCK.
RF interface: Pin 5= RF out, 46=RF in.

The device does not have a I2C interface. Both satelite receiver boards actually has two chips, one numbered CYRF693?, the other CY8C214. Can’t immediately found out what the latter is, but I assume it is taking the SPI output and translating the data onto a single bidirectional channel. as somehow between the little satelite receiver for the AR7000 and the processor in the main receiver they do switch from 6 wires (Vcc, MOSI, MISO, SCK, SS, GND) to a 3 wire connection (Vcc, GND, and ??).

Actually I have been looking at the product sheets for the transmitter and receiver chips used in the DX system. There are actually microprossors which have either I2C or SPI ports. So it could be that they output a digital stream to the microcontroler on the main deck which then translates that back to PWM modulated servo signals. I-ll have to look into that a bit further as this could be a significant simplification for my purposes. Why translate bytes to PPM / PWM and then translate back again ;=))

In fact if my supposition is right and the same would be the case at the TX end this would open up vast opportunities of insterting a microcontroler into the transmitter case which adds a few switchs to the case and resultant bytes into the data stream on the I2C bus and thus adds some channels

Within the transmitter there is certainly a PPM stream going from the human interface part into the transmitter proper. That is why it is possible to move the transmitter proper into a different (older) transmitter and get it to work like a DX6 or DX7. But most likely they do translate it into a byte stream in the microcontroler/transmitter stage.

I’m not sure I’m qualified to answer all your questions… sorry

In your first question, if you are talking about the three connectors for servos, then yes they are GND, V, and Signal. But as far as I know the signal that goes to the servos is PWM (Pulse Width Modulation), not PPM (Pulse Position Modulation). There is a positive going pulse every 50 Hz or so. If I remember correctly a pulse length of 1.5 ms corresponds to the middle position of the servo and the two extremes are about 0.5 and 2 ms respectively.

If you are talking about some internal connections within the receiver (for example between the RF stage and the servo outputs) then I doubt that Spektrum would use a PPM scheme for internal communication between the two processors. I do remember that some traditional radios on 35 or 40 MHz use a PPM modulation for the RF datalink, but I don’t know much about this – sorry.

hope this helps,

Anders

I-m looking at the possibility of interfacing a Spektrum receiver, probably the AR7000 to a microcontroler based flight stabilisation system. One of the two systems available for my use at the moment (http://www.mikrokopter.de/) wants to receive a single PPM datastream, not the demultiplexed separate servo outputs. Would I be correct in assuming that the three pints for the receiver connectors actually are GND, V, and signal, and that the signal would be the PPM datastream as seen by that receiver. If that is the case, would the processor be looking at these two datastreams and choosing the best one, demultiplexing that, and providing it on the servo outputs, but not providing the PPM stream chosen?

As an additional question, would the system be as uncritical of increased numbers of channels being fed in to the Tx and being received with respect to the PPM stream as normal FM systems? For the above system, the most used Rx actually only outputs 3 servo channels, but the exported PPM stream will have as many channels as transmitted.

Thanks up front for your reply.

that’s all I can help with for now,

Anders

Ps. maybe I should rip open my new DX6 + Rx also to see what’s inside them. And some people are getting the new Futaba 2.4GHz stuff now also – I need to convince them to let me open up everything and have a look.

Anders