From 84c7a7d6c134f88f89b639379c7b95534b203640 Mon Sep 17 00:00:00 2001 From: Mikael Nousiainen Date: Tue, 8 Aug 2023 18:34:18 +0300 Subject: [PATCH] Use Si4032 modulation type NONE for Horus 4FSK to produce a cleaner signal --- src/radio_si4032.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/radio_si4032.c b/src/radio_si4032.c index 2939d9b..effac50 100644 --- a/src/radio_si4032.c +++ b/src/radio_si4032.c @@ -70,7 +70,10 @@ bool radio_start_transmit_si4032(radio_transmit_entry *entry, radio_module_state case RADIO_DATA_MODE_HORUS_V2: { fsk_tone *idle_tone = mfsk_get_idle_tone(&entry->fsk_encoder); frequency_offset = (uint16_t) idle_tone->index + HORUS_FREQUENCY_OFFSET_SI4032; - modulation_type = SI4032_MODULATION_TYPE_OOK; + // Report from Mark VK5QI: https://github.com/mikaelnousiainen/RS41ng/issues/49 + // The use of OOK mode for sending 4FSK seems to be producing more transmitter sidebands than should be the case. + // -> The modulation type NONE produces significantly weaker sidebands, resulting in cleaner signal. + modulation_type = SI4032_MODULATION_TYPE_NONE; use_direct_mode = false; data_timer_init(entry->fsk_encoder_api->get_symbol_rate(&entry->fsk_encoder));