Not being a big-time VHF/UHF contester, please discount my opinion
appropriately, but I'm a systems guy and we can't pass up this sort of
discussion :-)
Here's an entirely different architecture for the radio. Some requirements
that the new architecure addresses:
- reduces low-loss feedline needs, particularly above 450 MHz
- provides a full digital interface for the User Interface
- provides for firmware upgrades and software-defined-radio features, such
as new modulation and data protocols
- allows TCP/IP connectivity to the Internet
- provides for third-party and independent software development
Within this architecture, the "radio as box" disappears in favor of a
distributed system of RF, processing, and UI subsystems. Nothing prevents
the user from assembling the three subsystems into a single physical unit.
This doesn't work all that well as a single all-band rig in a single
enclosure, but makes assembling a fixed station easier and cheaper.
To support this architecture:
1) The RF receive front-end should
- be capable of being completely remote-able as a unit, including
outdoor installation at the tower-top
- be sufficiently configurable to optimize dynamic range or sensitivity
- have common single-frequency downlink at a frequency (different from
rx) low enough to result in a large savings of feedline costs
- be capable of full-QSK single-band operation with a high-power
amplifier located in the shack
2) The RF PA should
- be capable of being completely remote-able as a unit, including
outdoor installation at the tower-top
- be capable of full-QSK
- have common single-frequency uplink at a frequency low enough
(different from tx) to result in a large savings of feedline costs
- be sufficiently configurable to optimize performance for individual
modulation schemes
3) The Processing subsystem should
- have an advanced DSP modulator and demodulator capable of anything
from CW to advanced I/Q schemes
- have a two-way digital high-speed (<1 msec event resolution) control
interface to the external modules
- have a public software interface for independent developers
- have a single-cable interface to the RF subsystem with the option of a
standalone control interface
- be capable of switching between several different RF subsystems with
full duplex operation
4) The User Interface should be either a standalone traditional front-panel
or a user-definable PC-based OS-independent interface
- the PC-based interface should include
- TCP/IP connectivity to the Internet to support transparent remote
operation
- standard connectivity to audio generation and processing
interfaces (i.e. - sound card)
- a public software interface
- support wireless human interfaces such as Bluetooth
- the interface between the UI and Processing subsystems should be a
Fast Ethernet or WiFi interface to a PC or standalone front panel
Obviously, there is lots more that could be added.
What about a fully digital interface to the RF subsystem using Firewire or
something similar? That also works. The tradeoff would likely be a more
expensive remote box and possibly a more complex interface involving
amplifiers. It's also possible that with a sufficiently high-speed A/D
converter, the processing subsystem could be subsumed into a PC, although
the hardware interface might be problematic.
Oh well, it's fun to think about!
73, Ward N0AX
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