J-INDEX (JIX) is an index value for measuring true MW reception conditions, kind of a "NASDAQ index for MW". Other common indices (such as A / K / solar flux and more) just describe space weather related geomagnetic characteristics but do not give a real MW-reception index value.
JIX is scaled from 1 to 100. By default, JIX is collected from the "overseas frequencies" based on the user's location. JAGUAR keeps track of signal levels on the first 100 MW frequencies (the overlapping NA/EU frequencies are excluded) and creates the averaged value which is named as the J-INDEX.
JIX offers an excellent tool for finding interesting spots when studying the recorded files. In addition, JIX can be used for comparing antennas and even QTHs (however, the effect of using an external preamplifier must be taken into account when comparing signal levels in two different QTHs).
The current JIX values are being automatically calculated when the hardware is plugged in, and the value is shown on PLAYBAR. JAGUAR calculates and collects two separate JIX values: one for MW10 frequencies and second for MW9 frequencies. If you change the MW frequency stepping, the JIX shown changes accordingly.
The JIX values will be saved to the YAS LOG file at one-minute intervals. In the ARCHIVE mode, the JIX values are read from YAS LOG and shown as red curves ("JIX CURVE") on some displays. The exact JIX values on those displays are shown based on the mouse position in a red "JIX ball". These displays include the 12-hour and 24-hour YAS LOG displays and the extended views of the spectrum.
Additionally, JAGUAR collects JIXHISTORY.LOG with hourly values for the MW10 and MW9 JIX. This log is used on the CONDX display (more details in the CONDX help) to compare classical solar index values (A / K / Kyoto / etc) with real trans-oceanic reception results (JIX CURVE). Note that the CONDX display can show the JIX CURVE only on the original recording PC as JIXHISTORY.LOG is saved in the JAGUAR installation folder. If you move your external hard disk to another PC for playback, the JIX CURVE cannot be shown on the CONDX display.
The JIX can also be used to automatically start recording when a user-defined threshold is reached. This feature is called AUTOREC (see GUIDE > MESTOR). Even though today's megatrend in MW DXing is to record everything overnight and use various analysis tools to see/hear the results, many users still prefer to record only the TOH times. In this case, AUTOREC can be combined with scheduled TOH recordings. In this way, all the good out-of-TOH openings will be recorded automatically. Or why not record only the "good openings"?
JIX is always collected automatically in the background.
When reviewing the JIX CURVE, you should look for the curve peaks (the sharper, the better!). Even a small peak in the curve can indicate a good spot for DX. Also, you should look for the times when the JIX value is rising/falling rapidly. Experience has shown that those times often offer the most interesting reception periods, e.g. perhaps dominants may have not faded in yet or may already have faded out, and the dial can be full of surprises. While in a DXpedition, we often monitor these rapid changes as a trigger to be especially alert.