Real-time & Remote SS1 Emulator and Analyzer
Selective Signaling "SS-1" is a 2 and/or 3 digit dial system used by the Federal Aviation Administration "FAA" within their National Airspace System
"NAS" Ground-to-Ground Air Traffic Control Network. It is used on leased and FAA lines between the Air Route Traffic Control Center's "ARTCC", Terminal
Radar Approach Control "TRACON", Air Traffic Control Tower's "ATCT", Lockheed Martin Flight Service Hub's "FS-21", Military, National Weather Service and
nongovernmental aviation facilities for the control and management of aircraft flights.
The GL's SS1 Analyzer detects and analyzes tone sequences that make up SS1 dial digits. Sequences of pulse and
guard tones are detected, decoded, and assembled into their corresponding dial digits. The tone sequences are also
verified for compliance against a "specification" parameter file which can correspond to published standards or user
The SS1 Emulator (Dialer) application provides the ability to setup and dial tone sequences that make up SS1 dial
digits. The applications' interface includes options to setup Dial Code, and control Mask (pulse) & Space (guard) frequencies
and duration, Initial, Nominal, and Final Durations, Timeout definitions, Transmit Channel, and other similar parameters
related to the dial code.
- Real-time and File-based) analysis
- Generate and introduce SS1 Dial Codes on Transmit Channels using SS1 Dialer
- Control mark & space frequencies and duration, and power during transmission of SS1 Tones
- Dual monitoring capability allowing multiple instances of SS1 analyzer to simultaneously tap E and W direction traffic.
- Ability to capture either TDM or audio signals
- Configuration screens to conveniently specify the criteria used to evaluate the sequence of SS1 tones, including
specifying the use of 2-digit or 3-digit dial codes. See the figure below.
- Display of received dial codes, including the characteristics of the underlying tones. Dial codes whose underlying
tone sequences do not meet stated criteria are clearly identified with the erroneous tone characteristics highlighted
- Provides controls to save sets of evaluation criteria, to reinstate previously saved criteria, and to reinstate factory
default (industry standard) settings
- Save results to files in a form that is widely understood by popular desktop data management and analysis tools
such as Microsoft® Access and Microsoft® Excel
- Allows easy reviewing any number of selected dial code sequences and their underlying tone sequences while
ongoing capture and analysis is proceeding
- Operate the SS1 Analyzer either remotely from the data acquisition site, or as on the same PC that is capturing the
- Examine a faulty dial code at length with Review Dial Code and Spectral Graph features, even as a run is in progress.
Specifying SS1 Evaluation Parameters
The SS1 Analyzer implements a wider range of values, which place lower and upper bounds on the FAIL range.
Measurements falling outside this range disqualify a signal from being an SS1 Signaling Tone.
The values are organized as follows:
- Standard: The standard value of the parameter.
- Low Accept through High Accept: Measurements within this range are judged to PASS the evaluation
- Low Reject through High Reject: Measurements within this range but outside the Low Accept to High
Accept range are judged to be MARGINAL.
Figure: SS1 Parameters
Parameter Scoring Options
- Pass/Marginal/Fail option - evaluates tones and their associated digits and dial codes records as PASS, MARGINAL,
- Pass/Fail: Marginal=Pass option causes all MARGINAL scores to be reported as PASSes.
- Pass/Fail: Marginal=Fail option causes all MARGINAL scores to be reported as FAILures.
Using GL's T1 Cards, one can internally capture signal data on a TDM channel or "timeslot". However, GL's T1 Cards
also provide VF Input and Output jacks through which you can insert an audio signal onto a designated T1 timeslot. If the
SS1 signals are being carried on an audio line, route that line into the VF Input associated with the T1 port, and then
For Offline analysis, SS1 analyzer allows users to specify the folder containing the files for SS1 analysis. File formats
supported are a-law, u-law pcm files.
The left pane (Tree View) shows the SS1 Dial Codes detected during a monitoring run displayed in protocol tree form.
Each Dial Code can be "expanded" to show the Digits at the next lower level of the protocol. The Digits can in turn be
expanded to show the sequence of Tones making up the digit at the bottom level of the hierarchy. The right pane (Tone
View) shows the elementary SS1 Tones that make underlie the dial codes shown in the tree view.
Figure: Analysis Results – Tone View
Figure: Analysis Results – Tree View
In Offline analysis, SS1 analyzer allows users to specify the folder containing the files for SS1 analysis. File formats
supported are a-law, u-law pcm files
- Analyze all files in a folder with a given file name extension, or
- Analyze a specific file.
Figure: File Selection
SS1 Protocol Analyzer is a client application and requires connecting to a T1 server. This allows SS1 Analyzer to be
used locally or on a remote PC w/o actual T1 hardware installation. Use the WCS Connection options to set all the
information required in order to establish a connection with the WCS server and correctly correspond with it.
SS1 Analyzer and the WCS server connection options -
- Connect to server on This PC option allows SS1 Analyzer to run on the Capture PC.
- Connect to server on… option allows SS1 Analyzer to run on a Remote PC
Figure: WCS Connection
Storage Options in Analyzer
Currently, only the CSV file format is supported by the SS1 Analyzer. This format is widely recognized by popular
Windows Data Management and analysis tools such as Microsoft® Excel and Microsoft® Access.
Table Name Prefix option allows users to designate a prefix for all files to be saved. The rest of the file name will be
made up of a text indicating the date and time of capture, followed by a suffix distinguishing between dial code, digit,
and tone records.
Figure: Dial Code & Digit Results in CSV files
Review Dial Code and Spectral Display Tools
It is quite likely that you will want to examine a faulty dial code at length, or view as a graphical waveform even as a
run is in progress. The SS1 Analyzer & Dialer provides an independent Review Dial Code, and Spectral Display window
options for this purpose.
Figure: Review Dial Code
Figure: Spectral Display
SS 1 Dialing Digits (Dialer) application provides the ability to setup and dial tone sequences that make up SS1 dial
digits. The applications’ interface includes options to setup Dial Code with control mask & space frequencies and duration,
and other parameters related to the digit dialer. Users can create channel for Transmission (Tx), choosing Port and
Figure: SS1 Emulator (Dialer)
- Key & Send – All digits are transmitted back-to-back with only the final space tone separating the
successive digits in a single burst.
- 2-Digit Burst – When the second digit is pressed, the digits are transmitted back-to-back in a single burst.
A "1" digit always triggers a transmission, even if it is not the last digit.
- 3-Digit Burst – same as 2-Digit Burst Dial, but Dial Code contains three digits. When the third digit is pressed,
the digits are transmitted back-to-back in a single burst.
- 2-Digit Direct Dial – the Dial Code are sent one-by-one as you key them. When two digits have been keyed
and transmitted, the Dial Code is transferred to the Dial History (Display).
- 3-Digit Direct Dial – same as 2-Digit Direct Dial, but Dial Code contains three digits. When three digits have
been keyed and transmitted, the digit record is transferred to the dial code display.
Please Note: The XX in the Item No. refers to the hardware platform, listed at the bottom of the Buyer's Guide, which
the software will be running on. Therefore, XX can either be ETA or EEA (Octal/Quad Boards), PTA or PEA (tProbe Units),
UTA or UEA (USB Units), HUT or HUE (Universal Cards), and HDT or HDE (HD cards) depending upon the hardware.
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