DAB/DAB+ digital radio in Thessaloniki, Greece

In a previous post I discussed the ERT DAB+ multiplex covering Athens, Greece. Recently the government controlled broadcaster ERT started transmitting a second  DAB+ multiplex from their transmitter site on Mt Hortiatis, near Thessaloniki. (HGRS87 coordinates: 423700, 4494181; WGS84 coordinates 40.5975 N - 23.1000 E; 871 m ASL).

This second experimental ERT transmssion on 174.928 MHz (Channel 5A) covers most of Thessaloniki and part of Central Macedonia Region. The multiplex contains the following audio streams:

"PROTO" (136 kbps,  AAC)
"DEYTERO" (136 kbps, AAC)
"TRITO" (136 kbps, AAC)
"ERA SPORT" (128 kbps, AAC)
"KOSMOS" (136 kbps, AAC)
"Voice of Greece" (96 kbps, AAC)
"ERA 7" (64 kbps, AAC)

The channel characteristics were logged in the afternoon of Sunday, April 29, 2018 using a Perstel DR70tc portable FM/DAB receiver at various locations in downtown Thessaloniki. 

A second multiplex under the name of "Sigmacom DAB+" is also transmitted from an unknown location in or near Thessaloniki on 225.648 MHz (Channel 12B). On April 30, 2018, it carried six private stations:

"YELLOW 92.8" (96 kbps, AAC)
"COSMORADIO" (96 kbps, AAC)
"KALAMARIA FM" (96 kbps, AAC)
"MORE RADIO" (96 kbps, AAC)
"AROMA FM" (48 kbps, AAC)
"PLUS RADIO" (96 kbps, AAC)

This seems to be an experimental transmission by local rado equipment supplier Sigmacom Broadcast Ltd. According to the official Digital Radio Allocation Plan for Greece, channel 12B would carry the 5th DAB multiplex for Thessaloniki area.

Update: Official service announcement by Sigmacom, 2018-04-30. Their transmitter site is also on Mt Hortiatis.