Future Autopilots

Proposed additions

We're always looking for great ideas. If you'd like to see something added or changed on Tiny v2.11 list it here! Please keep your suggestions relevant to this revision and post other requests in the Hardware Wish List.

• Separate GPS Option

see Twog_v1

• EMI filters on ADC channels
  

  On Semiconductor NUF4220MNT1G 4-line EMI Filter

Analog sensors are severely affected by video and modem RF. We typically see ADC reading fluctuations of +/-0.5% in a well shielded installation, but a misbehaving video transmitter or a noisy Radiotronix modem can affect ADC channels by more than 50% in the same well shielded installation. The addition of effective filters to the ADC inputs should greatly reduce the effects of RFI and allow for a much broader range of RF equipment and airframe configurations.

I suggest the On Semiconductor NUF4220MNT1G. A 2mm x 2mm chip that filters 4 analog signals, attenuatiing RF frequencies above 16 Mhz but particularly the 800 Mhz to 5 Ghz range. (Jeremy)

NUF4220MN is a 4 line LC EMI filter array designed for audio applications. It offers greater than -30 dB attenuation at frequencies from 800 MHz to 5.0 GHz, with no line loss. This part is a single chip solution for audio interface applications, 2 speaker lines with a microphone line. This device also offers ESD protection-clamping transients from static discharges and ESD protection is provided across all capacitors.

• Decoupling capacitor on GPS antenna

  The u-blox reference design calls for a 47pF 10% 0603 capacitor in series between the receiver and antenna. I have no idea why this is useful but apparently it must be, because this technique is commonly seen on WiFi cards, video transmitters, modems, even R/C receivers. Maybe we're missing out on something great? (Jeremy)

This is typically used as a DC block capacitor. Many RF amplifier circuits either require DC on their output to be powered, or have stray DC on the output. Also, many antennas are shorted at DC. The capacitor serves as a high-pass filter that allows minimal loss at RF frequencies. It isn't necessary unless the manufacturer specifies it.(hpux735)

• Filtering for GPS antenna

Make some sort of low pass or band pass filter to reject outside frequency's. This would be useful since most UAV's are not just used to fly but for video or other sorts of communication which tend to interfere with the GPS Signal. Maybe similar to some of these designs http://www.webx.dk/rc/video-wireless/filtergps.htm (Danstah)

Re: I have since found out that the lea-4p has a built in saw tooth filter. Adding a filter would probably only reduce the signal strength