Hi allI'm a student in Hanoi University of Technology, I'm building a system to communicate data between two computer like the figure
DSK6713 receive data from PC and make OFDM signal which are fed to the modulator TRF370417 my problem is that I have not connected between DSK6713 and TRF370417 yet, and had device to generator LO signal
to give modulator TRF370417. Beside that I want to ask you do I need a CDCM7005 Clock Gen like the figure :( .
I bought two DSK6713, TRF370417 and TRF371135 , would you give me some advices so I can complete my system.
From your diagram it looks like the DSK6713 generates an audio in and out signal. The TRF370417 accepts quadrature signals (I/Q). Likewise the TRF3711 produces quadrature signals. Are the audio in and out from the DSK6713 quadrature (I/Q signals) or just real signals?
If the DSK6713 produces quadrature signals then you do not need a DAC (DAC5687) and therefore you won't need a CDCM7005 device since that primarily is to drive the DAC in the diagram above.
You will need an LO source for the TRF3704 and TRF3711. The TRF3761 is a very high performance, but narrow band integer PLL/VCO. The TRF3765 maybe an option if you need a wider range of frequencies from your LO, its also a fractional PLL/VCO so hit can go to just about any frequency. The TRF3765 has 4 LO outputs so one chip could drive the TRF3704 & TRF3711 LO if the LO frequencies are the same.
You might want to check out the TRF372017 also, as it integrates the TRF3765 and the TRF3703/04 into one chip. Makes hardware design easier...
1. CDCM7005 provides clock for DAC5687. If you use DAC5687 to convert the digital baseband signal to the analog signal to feed to TRF370417, you need provide clock signals to DAC5687. You could find the DAC5687 datasheet which shows what the interface circuit b/w DAC and TRF270417 should be.
2. In your Figure 1, you directly connect DSK6713 to TRF370417. If DSK6713's output is a digital signal, you need to have a DAC, like DAC5687, to convert it to an analog signal as the input to TRF370417 I/Q input.
Thank you for answering. your advice is very useful.The signal which is fed to modulator is I/Q signal. but I have a problem
i want to ask you that what should I do in Convert module ?.
maybe I should connect direct I signal to I+ ( I positive), and I- connect to grown via a resistance.
or maybe I should design a circuit like that
If the I/Q outputs of DSK6713 are single-ended analog signal, you need to convert the signle-ended signal to a differential signal w/ 1.7V common mode voltage before sending them to TRF370x I+/I- and Q+/Q-. You could use a balun to achieve this.
now i'm having problem with TRF370417.
I have feeded LO signal into TRF370417 and its output signal is nothing
although it is good order at the previous time.
Please tell me how can I check that TRF370417 is in order or not ?
Sounds frustrating. Can you let me know what you have tried on the TRF370417 so far?
- with an oscilloscope can you view baseband signal at all 4 of the TRF3704's baseban inputs? What amplitude is this input signal? Can you measure the common mode voltage at the baseband inputs?
- Can you confirm that 5V reaching the TRF370417 supply pins
- Have you confirmed a LO signal is present at the LO pin? What amplitude is the LO signal?
- When an LO is supplied to the part, can you see the LO feedthrogh signal on the RF OUT pin with a spectrum analyzer?
- Are you implying that the TRF370417 on this board worked previously and now it is not working? Or do you mean the TRF370417 worked fine on one board and now on a different board it is not working.
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