DirecTV uses over 5GHz of bandwidth, broadcast from multiple satellites operating at different frequencies. You can't fit them all into one fiber. Their "old" system, with four-output LNBs, breaks them into four bands of 250 to 2150 Mhz. From there, a customer could either connect a single receiver to one of those ports, which would send control signal information in the form of DC voltage (13 volts or 18), simple tone frequency (22 KHz, either off or on) or DiSEqC data ( primitive, relatively low speed pulses formed with 22 KHz signals being turned off and on). One limitation of such a scheme is that one coax (or fiber) connection could only support one tuner, because two tuners on the same coax could only select from the roughly one fourt of the DiercTV programming that was on the coax at one time.
A couple of years ago, DirecTV released its "SWM" system, SWM stands for single wire multiswitch. The SWM system uses the technology of "agile stacking". The receiver sends a 2.3 MHz control signal to the SWM device, telling it which satellite and transponder it desires to receive. The SWM module then matrixes the signals from the correct satellite into a tuner, which selects the desired transponder and frequency-shifts it to SWM frequency #1, which I think is around 980 MHz. When the next receiver sends a signal upstream, the SWM module does the same thing and puts out the second desired transponder at around 1080 MHz. The SWM system does that with up to eight transponders. I believe it also sends a ninth, downstream signal with programming and control information at a frequency of close to 1900 MHz, but I've never looked into the technical particulars of it.
If you are using the terms Rx and Tx to refer to fiber transmitters and receivers that you intend to use, then those terms are ordinarily used to describe one-way devices. While your fiber itself can carry signals in two directions, I would not ordinarily expect an RF-to-optical converter to do that.
You can get by without two way communication if you have four fiber connections and four transmitters and four receivers running from the dish to the building, but that would also entail buying four transmitters and receivers (plus a fifth of each, because you will be the person servicing this system, and you will sometimes need to shot-gun swap in replacements to identify a malfunctioning unit). And in any fiber configuration, you will still have to power the SWM LNB with 18 to 20 volts. How can you do that without a copper connection from your building?
The cable companies send upstream signals for two-way communications with their boxes and also for internet upstream, and these systems commonly use upstream frequencies from 10 to 47 MHz, so there must already be some off-the shelf hardware for upstream communications over fiber, but that equipment may not work at 2.3 MHz, and multiplexing the upstream with the downstream may even require computer controlled switching at junction nodes. Toner Communications is one of the few CATV hardware dealers that sells both to large cable companies and to independent installers, so they may be able to tell you if they have any fiber solution that can send 250-2150 MHz DBS signal downstream and simultaneously carry 2.3 MHz upstream, but even then, if the 2.3 MHz SWM signal is two-way (which I am inclined to doubt), then products that work for cable TV sub band return would not work for SWM sub band communication.
I've never had reason to consider whether the 2.3 MHz signal is one way or two way, because the only SWM-compatible amplifiers presently available that I'm aware of use passive return paths because there is so much less coax path loss at 2.3MHz than there is at L-band frequencies. Someone at Sonora could tell you for sure. I wouldn't trust answers from anyone else - even from large MDU companies - because people hired to design and install even large L-Band systems are almost never engineers. They are told by a manufacturer that something will "work" in their application if installed a certain way, they try it, and then if it works reliably they continue to use it, but their jobs don't require understanding how the hardware actually does what it does.
This plan isn't going to fly at any price. Even if you can pull it off for $20,000, you still won't be remotely qualified to service it. You will approach each service call as a neophyte, since you won;t be acquiring any diagnostic expertise from any other systems you maintain, and any telephone support you can get from hardware manufacturers may be inadequate.
Remember, the leading edge is the bleeding edge, and if you buy and install something for $10,000 or more and the customer reports that it is intermittently failing them, how do you go about diagnosing and remedying the problem?
Realistically, the dish has to be connected to the building using conventional metal coax, and your opinion of the adequacy of surge suppressors carries insufficient weight with management, as it should. What you need is to get someone on his "team" to tell him that an exterior coax does not present a technical liability to the other equipment. You need to find out how he came to conclude or be concerned that the coax cable introduces a risk, and work back from there.
