Add HackRF Dgain detail, and capabilities.

1 files changed, 30 insertions, 12 deletions

diff --git a/scenarios.tex b/scenarios.tex
index f674be5..90ed7ba 100644
--- a/scenarios.tex
+++ b/scenarios.tex
@@ -154,15 +154,21 @@ following argument:
 --disable-output-uhd
 \end{lstlisting}
 
-ODR-DabMod has been tested to work with HackRF from Great Scott Gadgets on i386
+ODR-DabMod has been tested working with HackRF from Great Scott Gadgets on i386
 and x86 architectures.\footnote{HackRF has not been tested to any degree of
-    success with ARM-based computers at this time as they do not (yet) capable
+    success with ARM-based computers at this time as they are not (yet) capable
     of resampling to the required higher rates as the process is highly CPU
     intensive.}
-The unit is an entry level yet versatile SDR which
-provides for $\approx10$MHz to $6$GHz frequency coverage. To use HackRF one must
-configure the output of ODR-DabMod to produce 8-bit signed integers, rather
-than the default complex floats.
+The unit is an entry level yet versatile SDR which provides coverage between
+$\approx10$MHz to $6$GHz frequency coverage, and viable DAB signals been 
+generated with it in VHF Band III (174-240 MHz) L-Band (1462 - 1467.5 MHz) and 
+even the worldwide ISM Band (2400 - 2500 MHz). The latter (subject to your local
+regulations) is a licence exempt band which may be useful for performing freely
+radiating tests. Cheap MMDS down-converters are currently available which usefully
+provide a Band III IF output for DAB receivers.
+
+To use HackRF, the output of ODR-DabMod must be set (in the configuration file) to
+produce 8-bit signed integers, rather than the default complex floats.
 
 HackRF has selectable baseband filters, however the lowest filter setting
 ($1.75$MHz) does not provide adequate image rejection at the native sampling rate of
@@ -211,12 +217,24 @@ Depending on the capabilities of the host computer, using higher sampling rates
 it helps to produce a cleaner spectral output. At higher rates one needs to
 ensure that samples are not being dropped on the USB and that CPU resources are
 not being contended. It is also important to note that the digital gain value
-must also be scaled accordingly as the sampling rate is increased.
-
-HackRF has been measured with shoulder performance at $\approx 35$dB, which is roughly
-equivalent to that obtained from first generation commercial modulators. This
-can be increased to a relatively respectable $\approx 40$dB by enabling the FIR filter
-in ODR-DabMod, and an appropriate coefficient file provided.
+must also be scaled accordingly as the sampling rate is increased. Two sets of 
+values are provided which reflect the theoretical values, and the second set 
+given in parentheses are empirical maximum values determined while monitoring 
+shoulder performance (measured Δ970 kHz from the centre frequency) using a 
+spectrum analyser in ~3 kHz resolution bandwidth. The Digital gain figures for
+the tested sampling rates are shown below:
+
+Rate        Dgain   Max Dgain (Empirical)
+4096 ksps    2.0     2.25   
+6144 ksps    3.0     3.37 
+8192 ksps    4.0     4.50
+
+The shoulder performance has been measured with shoulder performance at a little
+better than 35$dB, which is roughly equivalent to that obtained from first 
+generation commercial modulator equipment. This can be increased to a relatively 
+respectable $\approx 40$dB by enabling the FIR baseband filter in ODR-DabMod, 
+and supplying it with an appropriate coefficient (tap) file. The maximum output
+power available to mmet these performance figures is approximately -10dBm RMS.
 
 Example of using ODR-DabMod with the \texttt{hackrf\_transfer} utility: