I would appreciate two little improvements/changes.
- 3.5mm 3 way jack instead of 2.5mm 4 way. - LEDs driven by external ICs, so they would be able to lit eve if FR is in suspend. I"m planning (-> which means that it may not even happen :-) ) to drive LEDs by I2C drivers, or to add some latch between the LED and FR's processor. Zb. Glenn píše v So 22. 01. 2011 v 23:22 +0100: > Hi All! > > Here are some hardware suggestion for discussion: > > > 1) Possibility of IR RC5 receiver/transmitter > > > 2) Possibility of IRDA transceiver > > > 3) Possibility of a "video-link"? Use > touch-screen as a color matrix (2D) barcode video > transmitter - and the camera as a receiver (half > or full duplex). Let the link automatically adapt > to to half duplex, if you need to turn your > smartphone to establish the other half duplex > connection. The link should also adapt frame rate > and if the camera and/or screen is dirty - or the > link is through a dirty window. I have no idea > how fast the link can be as a function of > distance. The link should automatically adapt if > the video color matrix (2D) barcode is mirrored > in any way - or "played" backwards. > > > 4) Antenna diversity of (preferably pattern, > space - or polarisation diversity): > > * GSM/UMTS? (receive diversity incl. external antenna). > > * 802.11(a)bg(n) (diversity) (W2CBW009Di: "For > Dual Antenna application") Almost every laptop > has diversity. > > * FM-receiver (receive diversity requires > 2*Si4721 - uC selects the best signal (listen to > one - let the other turn on and scan when the > listen-signal has to low S/N ratio) - or you can > listen to one and record another). > > * GPS? (receive diversity including external antenna). > > For FM-diversity you can use a 180 degree hybrid > (two loaded LC-circuits?) to separate common-mode > and differential-mode - for diversity - if three > space divided poles are available. I know that > there is a capacitance between ear-wires and > their ground, so I do not know, how well it will > work. Note that some impedance matching might be > needed. > > For VHF/FM the head-phone cable might be used. > The diversity might be implemented isolating > ground by a adequate inductor (100MHz parallel > LC-circuit) - and two high-pass filter from left > and right earphone non-ground wires - and the > GTA04 itself as a kind of "ground"/third-wire. > > - > > Links: > > Matrix (2D) barcodes: > http://en.wikipedia.org/wiki/Barcode#Matrix_.282D.29_barcodes > > PCB-antennas (small): > http://www.numatechnologies.com/pdf/foilantennas.pdf > > An antenna that can be sized for 100MHz reception > around the perimeter of the PCB? Use two loops so > ground is not needed: > http://www.hard-core-dx.com/nordicdx/antenna/loop/k9ay/k9ay_orig.pdf > http://www.hard-core-dx.com/nordicdx/antenna/loop/k9ay/index.html > > Also for 100MHz: > (T2FD -- The Forgotten Antenna: > http://www.hard-core-dx.com/nordicdx/antenna/wire/t2fd.html > ) > > > 1/3/2003 Antenna Diversity Strengthens Wireless LANs: > http://www.eetimes.com/design/communications-design/4008941/Antenna-Diversity-Strengthens-Wireless-LANs > Quote: "...While detailed implementations of > dynamic diversity can vary widely, it's possible > to summarize the simulated performance of a > conceptually simple scheme relative to that of a > single-antenna mode, as well as full diversity > and selection diversity (Figure 6)..." > > > http://en.wikipedia.org/wiki/Antenna_diversity > Quote: "... > Spatial diversity employs multiple antennas, > usually with the same characteristics, that are > physically separated from one another. Depending > upon the expected incidence of the incoming > signal, sometimes a space on the order of a > wavelength is sufficient. > ... > Pattern diversity consists of two or more > co-located antennas with different radiation > patterns. > ... > A polarisation difference of 90° will result in > an attenuation factor of up to 34dB in signal > strength. By pairing two complementary > polarizations, this scheme can immunize a system > from polarization mismatches that would otherwise > cause signal fade. Additionally, such diversity > has proven valuable at radio and mobile > communication base stations since it is less > susceptible to the near random orientations of > transmitting antennas. > ..." > > > http://web.archive.org/web/20060427002449/www.tvhandbook.com/support/pdf_files/Chapter17_7.pdf > Quote: "... > Diversity is only of value for the relatively > rapid fading caused by multipath. This kind of > fading is encountered extensively at HF and for > tropospheric and iono- spheric scatter > propagation at higher frequencies. Similarly, > mobile vehicles passing through a static > multipath field at VHF and UHF encounter such > fading as a result of their motion. > ..." > > > 180 degree hybrid: > http://upload.wikimedia.org/wikipedia/commons/6/62/Combine2.svg > "Sum" uses sum of ear-wires - and third-wire. > "Difference" to some extent uses only ear-wires. > > > Pattern Diversity: > 90 degree hybrid: > http://upload.wikimedia.org/wikipedia/commons/6/62/Combine2.svg > "X" uses ear-wires in one direction. > "Y" uses ear-wires in the other one direction. > > 180 degree hybrid and 90 degree hybrid might be > combined. One 90 and two 180 degrees? Then you > have 4 receive pattern diversity output ports. > > > http://www.option.com/en/products/products/embedded-mobile-broadband/lgamodulegtm601-609/specifications/#start > Quote: "... > Simultaneous Equalization and Rx Diversity on all > bands (Advance Receiver Type 3i), except for > GSM/GPRS/EDGE > ... > Primary, diversity and GPS antenna contact pads > ..." > > regards, > > Glenn > > _______________________________________________ > Openmoko community mailing list > [email protected] > http://lists.openmoko.org/mailman/listinfo/community > _______________________________________________ Openmoko community mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/community
