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DtvSignalMap  

Phase-Deploy
Updated Nov 17, 2011 by d4k...@hotmail.com

Introduction

DTV Signal Map monitors over-the-air digital TV signals and displays both a scrolling strip chart and a 2D map of signal quality by channel and antenna direction. It highlights all available TV signals and assists in aiming the antenna for best reception. It is written in Python 3 and currently works with [www.silicondust.com SiliconDust] HDHomeRun network tuners.

Operation

Run "signalmap.pyw" to start the application. The Tuners combobox will show the list of tuners discovered on your network. Select the desired tuner from the list.

The min, max and increment boxes control the range of channels and antenna directions scanned. Normal scan is by channel number, but for special purposes a frequency scan can be selected. The default channel range is 2-69, but in most areas there are no DTV channels in the low VHF band (2-6), and after the DTV conversion in 2009 channels 52 and above were reassigned for other purposes. Setting the scan range to 7-51 will usually find all available DTV signals.

The scan speed setting can be left on the default "Fastest". Slower scanning speeds may be useful when examining the stripchart in detail, but are not normally used.

The "Scan" button will start a channel scan, incrementing the antenna direction after each scan. The application currently prints a prompt each time the antenna is to be adjusted but does not pause for confirmation. Future versions will wait for user confirmation or automatically position the antenna if the rotator supports remote control.

The "Tune" button will tune to the "current" channel and display the signal on the stripchart to aid antenna adjustment.

The "Stop" button will stop signal monitoring, leaving the displays intact. It is necessary to stop when switching between scan and tune operation.

The "Reset" button will stop monitoring, erase the displays, and rescan the network to discover tuner devices.

The File/Save As... menu operation will save the signal map as a .csv file. File/Open... will load a previously-saved signal map.

Display

The signal map shows channels received (columns) by antenna direction (rows). Each map location represents analog signal strength in blue, ATSC modulated (8vsb) signal quality (SNR) in green, and digital symbol quality in red, thus viewable DTV signals appear on a spectrum from red (weak) through pink (medium) to white (strong). Blue areas of the map show signals too weak to obtain a signal lock or non-DTV signals.

While the application is stopped (not in Scan or Tune operation), a left-click on any point on the signal map will display the channel, antenna direction, and signal measurements at that point.

The stripchart shows signal strength (top - blue), SNR (middle - teal), and symbol quality (bottom - yellow) as the tuner scans through the specified channel range. The stripchart can also be used to monitor signal quality while aiming the antenna for a single channel.

Installation

Prerequisites:

  • Python 3 (tested on Python version 3.2.2, Windows XP SP3)
  • hdhomerun_config.exe (included with the HD Homerun software installation)

Steps:

  • Unpack the two Python scripts into the destination directory of your choice. No system administrator privileges are required.
  • If your HD Homerun software is not in the default location "C:\Program Files\Silicondust\HDHomeRun", edit hdhomerun.py to set variable "dir" in "runcmd" to the proper location.

License

DTV Signal Map
Version 0.1, 6 November 2011
Copyright 2011, David Kemp

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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