"RSQ"  signal report discussion

Background:
The traditional RST report was developed for CW communications to describe the quality of the code received by ear in terms of its Readability, Strength, and Tone.

PC sound card technology has recently enabled easy low cost access to a broad range of digital modes for the Amateur Radio operator. Many of the newer modes, such as PSK31 for example have become very popular, and as a result there is a significant increase in the activity of narrow band keyboard conversational modes on the HF bands.

Unfortunately the traditional RST (Readability, Strength, Tone) signal report is difficult to meaningfully apply to these text modes, causing the majority of operators to give contest style 599 reports regardless of the true merit of the received communication. RSQ (Readability, Strength, Quality) has been adapted from RST to provide a more useful signal report for HF digital modes.

RSQ Readability:  The new descriptive table has a corresponding range of percent readable text. This is consistent with the common practice of providing a percentage figure during a QSO or when responding to the inevitable “HW CPY?” at the end of an over. Currently, a percent readable text figure is often provided to the other station to clarify its readability after the traditional RST report has been sent.

RSQ Strength:  Most HF digital mode programs provide a broad band waterfall or spectrum receive display. As a result, it is common practice for operators to monitor and even decode multiple signals when working a narrow band digital station. Under these conditions, a visible measure of signal trace relative to noise is more meaningful than an S meter reading that averages the strength of all signals in the pass band.

RSQ Quality:  The presence of additional unwanted trace modulation observed on the waterfall or spectrum indicates possible spurious emissions and provides a basis for assessing the quality of digital mode signals. The traditional RST Tone report being designed to evaluate CW signals for the presence of audible hum, key clicks, chirping etc is simply not relevant to digital modes.

Click here to view the complete RSQ reporting table

IMD is still useful:

When viewing the trace of very strong signals, well-supressed additional sidebands may be seen above the noise floor. In this case, an IMD reading may assist in determining their status. If the IMD reading is about –25db or better, then any additional sidebands can be assumed as below the interference threshold, disregarded, and a Q9 report given. If the IMD reading is about –20db or worse, then the additional sideband modulation is undesirable, may cause interference to other stations, and an appropriate value from the quality table can be applied to the report.

It is suggested that IMD readings only be given to the other operator when requested, and then only as a supplementary report. This is because IMD is only valid for strong signals at idle, and after careful adjustment of receiver settings. However, an IMD measurement at the transmitter can be accurately undertaken, and is an excellent way to verify that the station setup is optimised.

Click here for a further discussion on IMD measurement.